When you assembled the table, did it have the tail ball catcher on the table area (where you added the sand), and did you receive two metal balls?
I think the mobile app or table firmware require an update to add the 2-ball features. I don't have it yet so I can't tell you specifics. When it is enabled, I believe two new tracks are added "attach" and "detach" which add and remove the second ball.
In tables and Minis that are 2-ball enabled, you will find two special tracks in your library: "attach" and "detach". As their names suggest, they attach / detach the "tail" ball. So you can either run "attach" as a single track, or you can put it into a playlist. When it runs, the second magnet will pick up the tail ball in the "ball-park" and bring it out into play. Every track after that will run in 2-ball mode. To go back to 1-ball, just run "detach" as a single, or put it in your playlist to automate it. Usually, if you create playlists that have detach and attach in them, you will want to run the sequentially (not shuffled). All tracks "run" in 1- or 2-ball mode. But usually, stuff that is recognizable (drawings of things, text, logos, etc) doesn't look good turned inside out :). Algorithmic stuff, on the other hand, can look great with 2-balls.
This is a bit cryptic now - but we will get more documentation out soon.