Find a 12v DC (Some AC's work) power supply, they are pretty commonplace with gadgets. They usually have the really fat plugs, and it will say 12v on it. Splice the wires, connect everything up, plug it in, and your fan awaits.
i got n old mobile phone charger chopped the end off, chopped the end off the comp fan,(i have 2 pc fans running off 1 12v plug) connected the wires!! Lovely!