I'm going to answer my own question, and make a suggestion:
On the N800, you can't right-click in this game. But there is a button at the left top (next to menu) called "actions". That button may bring up your right-click choices, so now you can play the game.

NOW: In Westnoth, the menu hard BUTTON does nothing, so: please, person who ported Westnoth to the N800: make the menu button do something useful, like "undo" or "rightclick".

Thanks.
- tobyr21