Plug a standard shielded connection cable into the mixer's main output. Depending on your equipment, the output will be balanced (low impedance) or unbalanced (high impedance) and will require either a 1/4 inch or XLR connector. Consult your owner's manual or manufacturer's Web site for specific information.
Plug the other end of the connection cable into the crossover's input jack.
Plug a connection cable into the crossover's high frequency output jack, and into the input jack of the amplifier that will drive the high frequency horn speaker.
Plug a connection cable into the crossover's low frequency output jack, and into the input of the amplifier that will drive the low frequency bass speaker.
Plug the speaker cable into the high frequency amplifier's speaker output jack, and the other end into the high frequency horn input jack.
Plug the speaker cable into the low frequency amplifier's speaker output jack, and the other end into the low frequency bass speaker input jack.
Set the crossover high and low frequency filters according to your crossover and speaker manual's recommendations. Power up the system and test for operation.