The easiest way to use a generator is to simply plug the equipment directly into the proper outlet on the generator. Never (ever) connect the generator's electrical output to the home's electrical circuits.
Never plug a generator into a wall outlet. You can also do it like this.

Determining which circuits you will require during a power outage is the first step in selecting the generator and transfer switch. Since most home appliances operate intermittently, a 5kW-10kW generator should be able to provide adequate power to essential appliances such as a microwave, TV, fridge, geyser and 10-15 lights.

Once the generator is running, you can also pick and choose which of the pre-determined appliances and circuits you want to use simply by flipping the switches on the sub-circuits board. It's important to keep track of amps because there is the possibility that you can use more appliances than the generator can handle all at once.