The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From A Banwasi:
Do you want find out more about your tennis game? Use myTennis. With myTennis you can record every point. It then allows you to drill down into each detail like number of unforced errors, number of aces and break points so you can review it and help you improve your tennis game. Ask a friend or parent to play the game along with you so you act on the detailed information and analysis. Recording points is very easy. The interface is a nice tennis court where you can mark each point, how each point starts and how the point ends. You can add as many tournaments you want and as many matches you want for each tournament.