Okay... for now, until you have some more specific problems I am going to point you at some MSDN docs that should help you out.
Google is also your friend.
The bottom line is you have to tell the application to start looking some where. Be it manually or you go and get a list of all the drives on the system.
http://msdn.microsoft.com/en-us/library/system.io.aspx
http://msdn.microsoft.com/en-us/library ... yinfo.aspx
http://msdn.microsoft.com/en-us/library ... einfo.aspx
http://msdn.microsoft.com/en-us/library ... etime.aspx
http://www.google.com/search?q=c%23+che ... ified+date
You are going to need to try a little bit before I help more. I need to see some code of your own and specific questions about the code. I can't do your homework for you.