Hi, can any one help me how to write a test method for the Apex callout ..

Here is the class:

global public with sharing class HttpCallout_CLS{
 public static String hitNumbertemp,dunstemp,compnametemp,compIdtemp,citytemp,countrytemp;
    String Accid = apexPages.currentPage().getParameters().get('id');
 
 Public static void sendRequest(){
    Integer i=0,j,k;
    String env;
    HttpRequest req = new HttpRequest();
    req.setMethod('GET');
    req.setHeader('content-type','text/xml');
    req.setTimeout(12000);    
    req.setEndpoint('http://xxx.com/API-32');
    String API_KEY = 'xxxx';
    Blob headerValue = Blob.valueOf(API_KEY);
    String authorizationHeader = 'BASIC ' + EncodingUtil.base64Encode(headerValue);
    req.setHeader('Authorization', authorizationHeader);
    String CName = apexPages.currentPage().getParameters().get('Name');
    env = '<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:sch="http://applications.dnb.com/webservice/schema/">'+
            '<soapenv:Header>'+
              '<sch:API-KEY>xxx</sch:API-KEY>'+
            '</soapenv:Header>'+
            '<soapenv:Body>'+
              '<sch:FindCompanyByKeywordRequest>'+
              '<sch:maxRecords>100</sch:maxRecords>'+
              '<sch:sortDirection>Ascending</sch:sortDirection>'+
              '<sch:keyword>'+CName+'</sch:keyword>'+
              '<sch:searchBy>companyName</sch:searchBy>'+
              '<sch:returnSearchNavigation>true</sch:returnSearchNavigation>'+
              '<sch:orderBy>CompanyName</sch:orderBy>'+
               '</sch:FindCompanyByKeywordRequest>'+
              '</soapenv:Body>'+
             '</soapenv:Envelope>';      
    req.setBody(env);
    System.debug(req.getBody());     
    Http http = new Http();
    HTTPResponse res = http.send(req);
              // *******Parsing XML Response *******
        Dom.Document doc = res.getBodyDocument();
    Dom.XMLNode envelope = doc.getRootElement();
    Dom.XMLNode body = envelope.getChildElement('Body','http://schemas.xmlsoap.org/soap/envelope/');
    Dom.XMLNOde keyWordResponse = body.getChildElement('FindCompanyByKeywordResponse','http://applications.dnb.com/webservice/schema/');
     for(Dom.XMLNode h1 : keyWordResponse.getChildElements()){  
          for(Dom.XMLNode child : h1.getChildElements()){      
               for(Dom.XMLNode h2 : child.getChildElements()){ 
                    if(h2.getName() == 'hit'){
                        for(Dom.XMLNode h3 : h2.getChildElements()){   
                           if(h3.getName() != 'companyResults'){
                                  hitNumbertemp = h3.getText();
                                }
                          else{                                           
                              for(Dom.XMLNode  h4 : h3.getChildElements()){
                                 if(i==0 || i==1 || i==2 || i==4 || i== 5 )
                                       {
                                           if(i == 0)
                                           {
                                             compIdtemp = h4.getText();
                                           }
                                           if(i == 1)
                                           {
                                              dunstemp = h4.getText();
                                           }
                                           if(i == 2)
                                           {
                                               compnametemp = h4.getText();    
                                           }
                                           if(i == 4)
                                           {
                                               streettemp = h4.getText();
                                           }
                                           if(i == 5)
                                           {
                                               citytemp = h4.getText();
                                           }
                                                                                     
                                           i++;
                                        }
                                       else if(i==15){
                                          WrapperClassList wrap = New WrapperClassList();
                                           wrap.duNs = dunstemp;
                                           wrap.comPanyName = compnametemp;
                                           wrap.companyId = compIdtemp;
                                           wrap.street = streettemp;
                                           wrap.City = citytemp;
                                           listWrapper.add(wrap);
                                          }
                                           i = 0;
                                       }  
                                       else
                                       {
                                           i++;
                                       }
                                   }
                           }
                        }      
                    }   
                }
                   
       }               
     }
}
  public List<WrapperClassList> getdataList(){
     return listWrapper;
  }
 
  public static List<WrapperClassList> listWrapper = New List<WrapperClassList>();
  public static Map<String,WrapperClassList> mapListWrapper = New Map<String,WrapperClassList>();
  public Class WrapperclassList{
      public String companyId{set;get;}
      public String comPanyName{set;get;}
      public String duNs{set;get;}
      public String street{set;get;}
      public String City{set;get;}
    
  }
 
}

 Thanks a ton in advance!

- Kumar