Purchase a ticket and join the fans at a game at Stade Roland Garros. If there's nothing happening while you're there, you might like to check if the stadium offers a tour of the facilities.
To visit this sporting facility, you'll need to find your way to 16th Arrondissement. You'll find lots of other things to see in this area, like Eiffel Tower, Louvre Museum, and Arc de Triomphe.