When it comes to serving in table tennis, the rules can be a bit tricky, but basically, you need to toss the ball up at least 6 inches and hit it so it clears the net and lands on the opponent's side of the table. A common mistake that leads to a fault is if the ball doesn't clear the net or lands outside the table, or if you don't toss the ball high enough. Also, you need to make sure your arm is behind the edge of the table and your hand is above the table surface when you make contact with the ball. If you're having trouble, try practicing your serve in front of a mirror to get a feel for the motion and make sure you're following the rules.