Creating a custom inventory GUI can be a little daunting ... I had some major problems with it when working on my first game.
Here is a thread I started for just this very question: Custom Inventory GUI
(it's in the Tech Archives - a great resource in there for future reference!)
As for the Save/Load GUI, your best bet (the way I learn the fastest) is to search the forums, find somebody else's code, and pick it apart. Then it'll be much easier to make your own.
Use the forum's search function (in the top bar up there!) It's indespensible!
Good luck!
Here is a thread I started for just this very question: Custom Inventory GUI
(it's in the Tech Archives - a great resource in there for future reference!)
As for the Save/Load GUI, your best bet (the way I learn the fastest) is to search the forums, find somebody else's code, and pick it apart. Then it'll be much easier to make your own.
Use the forum's search function (in the top bar up there!) It's indespensible!
Good luck!