These, along with other units like them, are very easy to install - they're just plug and play. All you do is to unplug a connector from the factory unit, plug it into the new one, and then plug in a harness from new to factory. It's basically a process of 'teeing in' the new unit between the car and the factory unit, so instead of wiring going from car > factory unit it now goes car > new unit > factory unit.
The most difficult process is getting the trim off and getting to the connectors in the first place, which is where YouTube comes in. No matter what you're doing, whether that be plumbing, painting, changing a water pump on the car, fitting a new laptop screen or whatever, someone will have done it before and uploaded a 'how-to' video to YouTube that you can follow.