global class Cmanfuct  {
        static string receiveToken(){
        system.debug('hit test');
        HttpRequest req = new HttpRequest();
        Http http = new Http();
        string endPoint;
        string client_id;
        string client_secret;
        if(!Test.isRunningTest()){
            CSS_Integration_Details__c recIntDetails = new CSS_Integration_Details__c();
            recIntDetails = CSS_getConnnectionDetails.getConnection('OAGOAuth');
            endPoint = recIntDetails.End_Point__c;
            client_id = recIntDetails.Username__c;  
            client_secret = recIntDetails.Passcode__c;
        }
        else{
            endPoint = 'https://abc.com/set';
            client_id = 'deerrr34';
            client_secret = 'wertyyy';
        }
        req.setEndpoint(endPoint);
        req.setMethod('POST');
        req.setHeader('Content-Type','application/x-www-form-urlencoded');
        req.setBody('grant_type=client_credentials&client_id='+client_id+'&client_secret='+client_secret+'&scope=CSSCloud');
      
        HttpResponse res = http.send(req);
       
        string jSONRequestBody = res.getBody();
        CSS_J2AToken_SRT wo1 = (CSS_J2AToken_SRT)JSON.deserializeStrict(jSONRequestBody,CSS_J2AToken_SRT.class);
        string accessToken = wo1.access_token;
        System.debug('BODY: '+res.getBody()); 
        System.debug('Status: '+res.getStatus());
        System.debug('Status Code: '+res.getStatusCode());
        return accessToken;
    }

   webservice static void sendClaimInfoToRSW(CSS_Job_Order__c recSJob){
      
       string jSONResponseBody = '';
       string cInfoRequest ='';
        try{
            string accessToken=receiveToken();
           
            System.debug('The cInfoRequest is***'+accessToken);
            String ServiceProviderCode;
            String DSID;
            String RONumber;
            String ESN;
            Decimal FailurePoint;
            String FailureMeasure;
            Datetime dtFailureDate;
            String FailureDate;
            Datetime dtWarrantyStartDate;
            string WarrantyStartDate;
            String Make;
            String Model;
            String Application;
            String VIN;
            String UnitNumber;
            String ServiceProviderContact;
            String CustomerName;
            String ComplaintCode;
           
            system.debug('recSJob.Creator_Location__c'+recSJob.Creator_Location__c);
            if(recSJob.Creator_Location__c != null){
            ServiceProviderCode = recSJob.Creator_Location__c.substring(recSJob.Creator_Location__c.indexOf('-')+1);
            }else{ ServiceProviderCode = ''; }
           
            system.debug('ServiceProviderCode'+ServiceProviderCode);
            if(recSJob.DSID__c != null ) {
                DSID = recSJob.DSID__c; } else { DSID = '';}
           
            if(recSJob.Shop_Work_Order__c != null )
            { RONumber = recSJob.Shop_Work_Order__c; } else { RONumber='';}
           
            if(recSJob.ESN__c != null ){
                ESN = recSJob.ESN__c; } else { ESN = ''; }
           
            if (recSJob.Failure_Point__c != null ) {
                FailurePoint = recSJob.Failure_Point__c; } else { FailurePoint = 0; }
           
            if(recSJob.Failure_Point_Measure__c=='Miles'){
                FailureMeasure = 'MI';
            } else if(recSJob.Failure_Point_Measure__c=='Kilometers'){
                FailureMeasure = 'KM';
            } else {
                FailureMeasure = 'HR';
            }
               
            if(recSJob.Failure_Date__c != null ){
                dtFailureDate = datetime.newInstance(recSJob.Failure_Date__c.year(), recSJob.Failure_Date__c.month(),recSJob.Failure_Date__c.day());
                FailureDate = dtFailureDate.format('YYYY-MM-dd') +'T00:00:00';     
            } else { FailureDate = ''; } 

            system.debug('FailureDate'+FailureDate);
           
            if(recSJob.Warranty_Start_Date__c != null ){
                dtWarrantyStartDate= datetime.newInstance(recSJob.Warranty_Start_Date__c.year(), recSJob.Warranty_Start_Date__c.month(),recSJob.Warranty_Start_Date__c.day());
                WarrantyStartDate=dtWarrantyStartDate.format('YYYY-MM-dd') +'T00:00:00';   
            } else { WarrantyStartDate = ''; }

            system.debug('WarrantyStartDate'+WarrantyStartDate);
           
            if(recSJob.Make__c != null ) {
                Make= recSJob.Make__c; } else { make = ''; }
            if(recSJob.Model__c != null || recSJob.Model__c != '') {
                Model= recSJob.Model__c; } else { Model= ''; }

            //String Application= recSJob.Application__c;
            if(recSJob.Application__c != null ) {
                Application = css_utility.getCodes('Application Code', recSJob.Application__c, null, null);
            } else { Application = ''; }
           
            system.debug('recSJob.VIN__c'+recSJob.VIN__c);
            if(recSJob.VIN__c != null ){
                VIN = recSJob.VIN__c; } else {
                    system.debug('VIN'+VIN);
                    VIN = ''; }
           
            if(recSJob.Unit_Number__c != null ){
                UnitNumber = recSJob.Unit_Number__c; } else {UnitNumber = '';}
           
            ServiceProviderContact = userinfo.getName();
            system.debug('ServiceProviderContact'+ServiceProviderContact);
           
            if(recSJob.Customer_Name__c != null ) {
                CustomerName = recSJob.Customer_Name__c; } else { CustomerName = ''; }

            if(recSJob.Category__c!= null ){
            ComplaintCode = css_utility.getCodes('Complaint Codes', recSJob.Category__c, recSJob.Complaint_Type__c, null);
            } else { ComplaintCode = ''; }  
            system.debug('ComplaintCode'+ComplaintCode);
           
            String JobId= recSJob.name;
          
            String UserId=  css_utility.getFederationId(UserInfo.getUserId()).toUpperCase();  //'OD324'; // User Id sould be in Upper case
            system.debug('UserId'+UserId);
           
            HttpRequest req = new HttpRequest();
           
            req.setEndpoint(CSS_getConnnectionDetails.getConnection('RSWClaim').End_Point__c);
            req.setHeader('Content-Type','application/json');
            req.setHeader('Authorization', 'Bearer '+accessToken);
            cInfoRequest= '{"Header":{"Sender":{"MessageID": "unique message ID at SF","SenderID": "SF","ServiceName": "ServiceRequest"},"Target":{"TargetID":"RSW"}},';
            cInfoRequest= cInfoRequest + '"DataArea": { "ClaimInformation": { "ServiceProviderCode": "'+ServiceProviderCode+'", "DSID": "'+DSID+' ", "RONumber": "'+RONumber+'", "ESN": ';
            cInfoRequest= cInfoRequest + '"'+ESN+'", "FailurePoint": "'+FailurePoint+'", "FailureMeasure": "'+FailureMeasure+'", "FailureDate": "'+FailureDate+'", ';
            cInfoRequest= cInfoRequest + '"WarrantyStartDate": "'+WarrantyStartDate+'", "Manufacturer": "'+Make+'", "Model": "'+Model+'", "Application": "'+Application+'", ';
            cInfoRequest= cInfoRequest + '"VIN": "'+VIN+'", "UnitNumber": "'+UnitNumber+'", "ServiceProviderContact": "CMARINE", "CustomerName": "'+CustomerName+'", ';
            cInfoRequest= cInfoRequest + '"ComplaintCode": "'+ComplaintCode+'", "JobId": "'+JobId+'", "UserId": "'+UserId+'" } } }';

            System.debug('The Claim Request is***'+ cInfoRequest );
            req.setBody(cInfoRequest);
            req.setMethod('POST');
            Http http = new Http();   
            HTTPResponse res = http.send(req);
            jSONResponseBody = res.getBody();
            if(jSONResponseBody.contains('ERROR')){
                System.debug('Incorrect json format');
                System.debug('BODY: '+res.getBody());
                System.debug('STATUS:'+res.getStatus());
                System.debug('STATUS_CODE:'+res.getStatusCode());
                css_utility.LogOutIntError(cInfoRequest, 'CSS Error:' + 'External Service Error',jSONResponseBody,'RSWClaimInfo');
            } else if(jSONResponseBody.contains('DEVELOPMENT MESSAGE')) {
                css_utility.LogOutIntError(cInfoRequest, 'CSS Error:' + 'External Token Error',jSONResponseBody,'RSWClaimInfo');
            } else {
                // Success
                System.debug('BODY: '+res.getBody());
                System.debug('STATUS:'+res.getStatus());
                System.debug('STATUS_CODE:'+res.getStatusCode());
            }
        }
        catch(exception e){
            system.debug(e.getMessage());
            css_utility.LogOutIntError(cInfoRequest, 'CSS Error:' + e.getMessage(),jSONResponseBody,'RSWClaimInfo');
        }
    }
}

 
We have a requirement to create a REST Service that will send Data from a Custom object on click of a Button. how we can achive please help  me