How to get start & end time of session in asp.net c#

Question

Hi all, I am working in asp.net c#.

I have one user login page having userid, password fields & Go button.

After login user gives the mcq test & then sign outs by clicking on Logout link present at the corner of page. Session starts when user clicks on Go button & ends when user clicks on Logout link.

I want Start time & End time of this session which I want to save in a sql database database as LoginTime & LogoutTime in datetime format.

Thanks in advance.