Google is your friend: Be nice and visit him often. He can answer questions a lot more quickly than posting them here...
A very quick search
using your question as the search term gave over 70,000 hits:
Google: "how to create the gmail login page using Watin concept in C#"[
^]
Follow a few of those links, and see what you get...
In future, please try to do at least basic research yourself, and not waste your time or ours.