In the first point of each game, players serve from the deuce court (ie the right hand side of the court). If they miss the first serve they hit their second serve from the same position. They alternate between the left and right side each point.
Except for tie-breaks. The first person to serve in a tie-break serves for one point on the right hand side. The next person to serve then starts from the left hand side and serves for two points. After that, the players continue to serve for two points, starting on the left hand side each time.