The dots represent soldiers and the line indicates the starting position of your troop. Your goal is to move as north as possible from this starting line. The visibility of this line is toggled using "Show line".
You can make moves when "Edit" is unchecked. To make a move:
You can edit the board when "Edit" is checked. To edit the board just click on the location where you want to put a soldier. Optionally, you can click "Update line" to update the position of the starting line.