help wiring to fuse box

I have 2 12" neons under my seats i have all the wires and i know a little bit about wiring i have had them wired to a toggle to the battery, but i wanted to wire them to a fuse in the box. i have the "not used" spots but they have i guess no power to them is there anythign i can do to get poer to them or wire it the the fuse box using a fuse? i dont want to wire them to a fuse already used because then ill blow it and the thing the fuse is hooked up to wont work either please help fast, my truck is sorta waiting out side right now because im tryign to figure this out. any diagrams or ANYTHIGN will help thanks.