Hold the boomerang near vertical and whatever you do, do not throw it horizontally. Let the round painted side face you and the flat side face away from you. To give the boomerang a curve, simply flick it out of your hand. Also grip it tightly.
One very important thing to remember is that a right handed boomerang slightly curves anti clock wise and a left handed boomerang slightly curves clockwise.
If there happens to be wind stand so that it is coming towards you then turn to your right slightly. Then throw harder than you normally would.
To catch the boomerang you need to put one over the other leaving a small gap. When the boomerang comes in between them quickly clap your hands together.
If you are scared to catch the boomerang or are a beginner I would suggest using an Omega boomerang. Both of its end points are twisted so that it is easier to throw and catch. This also slows down the speed of the boomerang.