there is nothing like "#" in http://localhost:0003/index.aspx#access_token=qwqwqwqwqw

that got to be "?" so it becomes http://localhost:0003/index.aspx?access_token=qwqwqwqwqw

that is what you call querystring and you can access it on index page like this:

string qstring = Request.QueryString["access_token"]; //C#

Dim qstring as string = Request.QueryString("access_token") //VB

More info:

http://www.dotnetperls.com/querystring

http://www.codeproject.com/Articles/5876/Passing-variables-between-pages-using-QueryString