Left brake light not working

I replaced the bulb but still nothing. All the other lights are working in the left assembly are working fine. I've never worked on a car's electrical/wiring system so I'm looking for some trouble-shooting tips. (detailed tips :) )

buy a test light. get in the trunk,pull back the carpet on the left side find the wiring to the tail lights, i beleave the connectior has 5 wires. black is ground, i can't remember what the brake light is. you will need to play around to figure it out. see you have power for the brake there. if you do, recheck the bulbs and sockets. if you don't, follow the wire up to the next connector and retest. try to find where you are losing the connection.