hello i am develop a online test application.. have a some problem

hello..
I am develop a Online Test Application. I have some problem.
1.When student login page then he go to student home page and click on start page .then next page will be display 30 Question.
I have write top of this page Do'nt Refresh Page .I want when page is again load then my session expried and result  insert in my result table.
2.When any student which have logged click on back button browser then my session is expired andand result  insert in my result table.
3.I have make countdown time when time is over of logged student then session expired and dand result  insert in my result table.
But i enable do these task ..pls tell me ..
How do this .
Asp.net.

Thanks