Hi ALL, how to write test method for the following code..

global class InboundLinxUserRegistration {
     global class dtRegistrationInput {
       webservice ID UserId;
       webservice String First_Name;
       webservice String Last_Name;
       webservice String Email_Address;
       webservice String Status;
       webservice ID Workplace_Id;
       webservice String Workplace_Name;
       webservice String Workplace_Province;
       webservice String Workplace_City;
       webservice String Workplace_Postal_Code;
       webservice String Workplace_Address;
       webservice String Speciality;
       webservice String Record_Type;
      }
     global class dtRegistrationOutput {
       webservice date mydate;
       webservice String added;
       webservice String status;
       webservice String Message_Text;
       webservice String error;
     
      }
    
      public webservice static dtRegistrationOutput registration(dtRegistrationInput userregistration){
           dtRegistrationOutput registration=new dtRegistrationOutput();
           List<Account> account = [select National_Code__c,PersonEmail from Account where National_Code__c=:userregistration.UserId OR PersonEmail=:userregistration.Email_Address];
          if(account.size()>0){
                     registration.mydate=system.today();
                     registration.added='false, http status code=200';
                     registration.error='Duplicate';

          }else{
                     Account acc=new Account();
                     acc.National_Code__c=userregistration.UserId;
                     acc.FirstName=userregistration.First_Name;
                     acc.LastName=userregistration.Last_Name;
                     acc.PersonEmail=userregistration.Email_Address;
                     acc.Account_Status_NES__c=userregistration.Status;
                     acc.Primary_Parent_vod__c=userregistration.Workplace_Id;
                     acc.Primary_Province_NES__c=userregistration.Workplace_Province;
                     acc.Primary_City_NES__c=userregistration.Workplace_City;
                     acc.Primary_Postal_Code_NES__c=userregistration.Workplace_Postal_Code;
                     acc.Primary_Address_1_NES__c=userregistration.Workplace_Address;
                     acc.Specialty_1_vod__c=userregistration.Speciality;
                     acc.RecordTypeId=userregistration.Record_Type;
                     try{
                         insert acc;
                         registration.mydate=system.today();
                         registration.added='True,http status code=200';
                         registration.Message_Text='Registration Successfull';
                        } catch (Exception e){
                          registration.mydate=system.today();
                          registration.added='false';
                          registration.error=e.getTypeName();
                          registration.Message_Text=e.getMessage();
                         }
                   
                }
            
             return registration;
           
                                
       }
  }