How do Boomerangs come back to you?

A boomerang comes back to you because its wings are shaped and angled to emulate a plane's wing. Because the two wings are facing in different directions they create a pulling force that makes the curve shape of its flight pattern
The shape of the boomerang causses differences in the air pressure above and below it, and as it spins, this air pressure difference causses the flight of the boomerang to make a slow turn, which eventually brings it back to where it started (the flight can be adjusted by winds however, causing the flight path to distort and it will come back slightly off from where it started.
Because the air that hits one side hits the other side in the opposite direction, that makes the boomerang turn around and come back to the direction it is pointing when turning around.