One of the pre-built Players in the GGP codebase is called the Human player. It lets you control its moves. This is useful if you want to create a specific sets of moves for your Player to play against. To use it, select Human from the Player manager's drop-down menu.  The tricky part is understanding to make it play. 

Every time you select a Player a tab is created in the Player Manager for that player. For the most part you can ignore that tab. But for the Human player you need it to control the moves. Click the Human tab. Then click the Detail sub-tab. When it is your turn to play, a list of the legal moves will appear in that tab. The first one will have been selected by default and displayed in the bottom field. To select a different move, click it and then click the Select button. Confusingly (at least for me) clicking Select doesn't actually cause the Player to make that move. It simply puts the move into the field at the bottom of the Detail tab. When time has elapsed, the player will take whatever move is there and play it.

To try this out, you might use it for the Three puzzle.