It is classified in four tabs: Equipment, Use, Set-Up and Etc. based on the characteristics of the items.
Place the cursor over the item, and you'll see the required skill level and the item's effectiveness in detail.
The mesos that the character possesses are also displayed at the bottom of the screen.
The "use" items can be placed in the HotKey's for quicker, easier use.
The Hotkey: ( I )