Internal Server Error with asp.net Website

I am building a website through Visual Studio with asp.net but when I try to run the index page which is the default.aspx, it generates an Internal Server Error.
What is the correct configuration in order to run the page correctly?
Help please.

Server Error
Error Summary
HTTP Error 500.19 – Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.
