PLEASE HELP ME IN ASP.NET DEBUGGING?

hello freinds, I am not being able to debug any of the asp.net webpages which i develop on my computer with c# backend. Whenever i debug windows application it gets debuged perfectly but when i try to run asp.net webpages even though the code is correct the browser page says that page can not be found it is the problem with every asp application i develop i have tried with all the different browsers... please help me to fix this problem.... please