"output the condenser" ? or "output to the compressor" ?
The Behringer 1604 doesn't have "insert" points (that is where you would usually want to do it)
It depends on what you are trying to do:
1. Compress only the mike, and it is the only thing you are recording ? Put the compressor after the outputs of the mixer.
2. Compress ONLY the mike, but then mix it with other sounds before going to recorder ? Send the mike to the Aux bus outs. Run it into the compressor, then back into another channel of the mixer, sent to main outs where it is mixed with the other sounds and goes to the recorder.
3. Compress the whole mix: mike+other stuff.
Just put the compressor after the mixer main outs.