this is a class. this function returns scalar value. how to take that value in code behind and assign this return value to customer id

public int InsertRegistrationDetails()
 { 
 SqlCommand cmd = new SqlCommand("sp_Registration",con);
 cmd.CommandType = CommandType.StoredProcedure;
 cmd.Parameters.Add("@CustomerId", CustomerId);
 cmd.Parameters.Add("@EmailId",EmailId);
 cmd.Parameters.Add("@FirstName",FirstName);
 cmd.Parameters.Add("@Lastname",Lastname);
 cmd.Parameters.Add("@Phone1",Phone1);
 cmd.Parameters.Add("@Phone2",Phone2);
 cmd.Parameters.Add("@CompanyName",CompanyName); 
 cmd.Parameters.Add("@Address",Address);
 cmd.Parameters.Add("@ZipCode",ZipCode);
 cmd.Parameters.Add("@City",City);
 cmd.Parameters.Add("@State",State);
 cmd.Parameters.Add("@Country",Country);
 cmd.Parameters.Add("@TransactionDate",TransactionDate);
 cmd.Parameters.Add("@Status",Status);
 cmd.ExecuteNonQuery(); 
 int NewId = 0; 
 NewId = Convert.ToInt32(cmd.ExecuteScalar().ToString());
 return NewId; }