The three ranks furthest from you are the promotion zone 敵陣 — for Sente on this board, ranks 7, 8 and 9; for Gote, ranks 1, 2 and 3.
When one of your pieces makes a move that ends in the zone, starts in the zone, or both, you may turn it over to its promoted side. The board asks you with a Promote / Keep choice whenever you have one.
Moving in
Moving within, and moving out
A piece already in the zone may promote on any move — even one that leaves the zone again.
Promotion is usually a choice. Promoted pieces are generally stronger, but not always better: a silver loses its backward diagonals when it promotes, and sometimes you want to keep them.
The king and the gold never promote.
Try it
Try it: Move the silver into the zone and promote it (choose Promote when asked).