How to use timer in ASP.NET

Question

Hi all

I have to use a timer. The time is in format 00:00:00. I have to made this timer for bidding site. There is an opening time for bid. And bid has to be started after some time lets after 02:43:30.This time should be decremented to 00:00:00. after this the timer will start at 00:00:30 the timer will be decremented to 00:00:00. when a person hit the button (make a bid) in a meanwhile then after that it again start with 00:00:30.

Please help.Send me the code or any logic that will help me. The timer should be like

http://www.bidrivals.com