I need help with 90' civic wiring problem!

I just bought a 1990 Honda Civic Hatchback, and have been pulled over twice so far for my tail lights being out. I've replaced ALL the bulbs and fuses! Still...nothing. :-( I can't afford to take it into a shop because they charge of the rear and I just put all my money into buying the flippin thing, what do I do?
If anybody can give me a run threw on where to start so that I could fix it myself I would SOOOOOOOOOOOOOOOOo appreciate it. Really.

if you recently added an aftermarket deck, sometimes the wires will short against the metal back there causing them to blow the fuse (radio and tails are on same fuse) id check that first.

The deck was proffessionally installed. Last night I took the dash apart and wiggled the wires around the stearing wheel...it made the lights work...probably not for good, but atleast I know where the short is right?

looks like you got a loose wire. now go find it and fix it. its the switch on the drivers side of the steering wheel