flucks

Lately i've been having trouble with my stereo's left channel going out in my pickup and have no clue whether its the stereo or the stereo. I don't know anything about car stereos nor about how to get back there to see whats wrong. How would i go about getting behind the stereo to make sure everything is okay in there? What all do i have to take off and whatnot? Any help with this would be really appericated, especially since only having a right channel is driving me insane.