I tried a game, and got to where I wanted to castle but couldn't figure out how to tell the game I wanted to do that. How does one go about that? Also, if I want to retract a move before my opponent moves, how do I do that?
You can't retract moves unless you are playing an unrated takeback game. To castle you move your rook two squares towards the rook you want to castle with, if all castling conditions have been met.
I tried a game, and got to where I wanted to castle but couldn't figure out how to tell the game I wanted to do that. How does one go about that? Also, if I want to retract a move before my opponent moves, how do I do that?