UserName being passed in a cookie

I am trying to get the UserName of my website members to pass from the default ASPNETDB database login control to other members-only pages. I assume the best way would be to use cookies. I have tried to do the ASP.net cookie tutorial, but it has not helped.
Can someone give me some code to use? Also, I need to be able to query a sqldatasource in the WHERE (username = @UserName) in the cookie. If you could help me with that too, that would be great.
Thanks.
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