Hello all,
I am new with Apex and Salesforce so bare with me.
Up until now all the triggers I have written work just fine in Dev/QA and production.
But now I have this one trigger that needs a test class, but I am not sure where to being.
If someone can help me develop a test class that for the trigger below, then I should be able to understand how to test my triggers in the future. How to get the data needed to test the triggers ect...
Thanks,
Keith.

trigger MostRecentCenter on Procedure__c (after insert, after update) {
   try{           
            
           Set<Id> procIds = new Set<Id>();
           Set<Id> caseIds = new Set<Id>();
       List<Case> lstCase = new List<Case>();
               
               for(Procedure__c proc : Trigger.New)
               {                 
                   if(proc.CreatedDate != null) 
                   { 
                       procIds.add(proc.LastModifiedById);  
                       caseIds.add(proc.Case__c);                      
                   }                        
               }                        
               
              Map<string, Procedure__c> procMap = new map<string, Procedure__c> ( [SELECT CenterID__c, Center__c from Procedure__c 
               where LastModifiedById IN: procIds Order by CreatedDate Desc] );     

              Map<string, Case> caseMap = new map<string, Case> ( [SELECT Id, Most_Recent_Center__c FROM Case WHERE Id IN: caseIds] );  
                         
                 for(Procedure__c pd: trigger.new) 
                 {       
                     //system.debug(pd.id);

                    if(procMap.containsKey(pd.id)) 
                    {                 
                      
                        //Id centerID = (Id)procMap.get(pd.id).Center__c;
                        //Case cs = (Case)[SELECT Id, Most_Recent_Center__c FROM Case WHERE Id = :pd.Case__c];
                        //cs.Most_Recent_Center__c = centerID;
            caseMap.get(pd.Case__c).Most_Recent_Center__c = procMap.get(pd.id).Center__c;
                        lstCase.add(caseMap.get(pd.Case__c));                      
                                                               
                    }       
                }
                //system.debug(lstCase.size());
        if(lstCase.size()>0)
          update lstCase;
                
          //  }    //End of trigger.isBefore
        
    }catch(Exception e){
       //Package suspended, uninstalled or expired, exit gracefully.
       System.debug('MostRecentCenter');
    }
    
}