It's quite simple to use this nifty tool. First, decide what kind of hole you need to cut. Do you need a rectangular or a square hole? Depending on the desired hole, choose the right model to cut your slot. If you're going to put a wall socket in the hole, make sure you check it's the right size.
The blade is compatible with any standard oscillating multi-tools. You only need to attach the saw blade, either the square one or the rectangular one, and start using it. Using a simple punch movement, you'll have your slot done in no time!