Racquetball matches are completed in a best-of-three-games format. You can only score points when you're serving.
Decide who will serve first. There are numerous ways to decide, including flipping a coin or spinning a racquet. (Call heads or tails or choose insignia up or down.)
Serve the ball, accumulating points until the other person/team wins a rally or until you fail to play a serve legally. Each time the rally ends in your favor you earn a point. When the receiving team wins a rally, it's called a sideout (similar to volleyball).
Announce the score each time before serving the ball.
Continue until one person/team reaches 15 points. A one-point advantage constitutes a win (15-14).
Allow the person/team that lost the first game to open service for the second game.
Play the third game to 11 points if necessary. The person/team that accumulated the most points in the first two games gets to serve first in the third game.