If you're installing an AIO watercooler, mount the radiator at an appropriate point in the case (at the front or rear air intakes/exhaust are common) and attach the fan's header to the correct port.
If you're installing an AIO watercooler, mount the radiator at an appropriate point in the case (at the front or rear air intakes/exhaust are common) and attach the fan's header to the correct port. You may also need to attach the pump header, which some motherboards have specific ports for.