It sounds like you already have it wired up, but if you got one of these it just plugs in your existing wiring.
http://www.etrailer.com/Custom-Fit-V...id=20101172310
If you don't travel far or have too many hills you can do without the trailer brakes otherwise I would recommend getting a brake controller. If you haven't noticed already, even with an empty trailer, you do get quite a bit of push from the trailer when stopping. The controller doesn't hook up to the electronics of the truck so your computer should not be affected.
http://www.etrailer.com/Brake-Contro...sha/90195.html
What kind/size trailer do you have?