Scripting help

[Irgna]

I'm working on an edit to the DMS as my first script (yay), and I need to know how to make it so the Options (Items, Skill, Equip, Status, ect.) box have an icon at the bottom and when I press down at the bottom choice it erases the icon and put a new one at the top of the box and reveals more options.

Edit: Here are some screen to show what I'm talking about.
Top:


Bottom: