Making an inventory in a seperate frame

Right now i have an inventory, but it is on the same page as the character and the map and stuff. I am trying to get it so when you pick up an item that it will go to a seperate frame or something. Like just an inventory page. And then I would need to know how to go back to the main screen from where you left off. If you have any piece of info or anything it would be much appreciated.