Script to create Triggers

Hi Guys,I would like to create triggers for the following items in a table for auditing purposes. Could you please provide script for this.Table name: [Users]Audit Column names: ============= Aud_Create_User (Use SYSTEM USER) Aud_Create_DateTime (Use create datetime) Aud_Update_User (Use SYSTEM USER)Aud_Update_DateTime (Use update datetime)Do I need to use trigger for [Aud_Create_DateTime] field or can we use constraint to use getdate() ?Many thanks in advance!