Dear Session is an object which contain information which you want to carry over
Suppose in your page1.aspx there is a test box whose ID is txt_user and a button
And if you want to use this test into next page lets say it is page2.aspx
You have to use like this
For a button click event
use session object
Session["your_session_variable_name"].ToString()=txt_user.Text;
and this will contains the text box value in session variable then you can use it in next page like this
String your_name=Session["your_session_variable_name"].ToString();
And now you can use this string till the session ends by default or you kill it