Buy tickets and join the fans at a game at Prince Salman Sports City. If there's nothing happening while you're in the area, you might like to check if the stadium offers a tour of the facilities.
You'll have sightseeing choices galore when spending time in Al Majmaah. Prince Salman Sports City is a great place to begin here, but there are many other worthy places to enjoy. Mountain Oasis Park, and Majmaah University are close to the sporting facility and will top off your day nicely.