How to determine the backpack keys (1-0) and if they're being pressed or not?

I am making a script currently that makes the BackpackUI disappear if you don't press the keys after 5 seconds. I don't know what to determine the keys would be called, or how to make the script know whether or not you are pressing the keys. If anyone can help me on that, it'd help. Thanks!

You are going to want to use this.. http://wiki.roblox.com/index.php?title=KeyDown_(Event) (That will help you with understanding how to code when a person presses a key..)

And..

http://wiki.roblox.com/index.php?title=CoreGuiType (This will help you with removing/adding the players backpack)