Connect the "Direct Out" jacks from your mixing board to the corresponding input jacks of your multitrack recorder using 1/4-inch unbalanced patch cables.
Connect your microphone or line level audio source to the input connections at the top of each channel of your mixing board.
Monitor the level meters on your multitrack recorder while adjusting the trim or gain knob of each channel of your mixing board. Try to set a level for each channel so that the loudest sounds do not push the multitrack's meters into the red.