tunedup

i know this shud go in the audio forum but this is 911.
i got a 4 ch amp 800 i need to bridge it to 2 ch
i got one side to work and i set the gain and everythin on one side
the other side wont work.
i check the connections numerous times
in the back of the amp theres 3 pairs of inputs
input rear
input front speakers
and output.
right now i have an output from the amp connectin to my line level
plz help.
is there somethin im doin wrong