On the auctions page, there will be three things. A text input box, if you know the specific item name or keyword. A “usage” checkbox, to denote the kind of item it is. And a clbum (category) check box for the actual items themselves.

What you want to do, for example: computers, is click the “toggle all” on the right checkbox to clear the fields and click the box by “computers” to pull up all computer files. Simple as that.