Find two other players who are relatively equal to you in tennis talent and experience. Make certain the court on which you play has doubles alleys. Nearly all do, but there are exceptions.
Have one player on one side of the court and two on the other. Understand that the singles player is allowed to hit the ball into the doubles alleys. The doubles team is not.
Play a set. The usual tennis rules apply. When a player from the doubles team is serving, her partner can play back or up at the net. It is his choice.
Rotate after each set. Give all three players a chance to hit singles. The singles player who wins the most games is declared the overall winner.