Follow the article in the link below:
http://sharepoint.infoyen.com/2012/03/13/pass-page-values-from-one-to-another-page-in-asp-net/
Bruce Ng's software development blog
An archive of solutions of programming problems I have faced in my career
http://sharepoint.infoyen.com/2012/03/13/pass-page-values-from-one-to-another-page-in-asp-net/