to add to the above, do NOT TURN when you first start rowing. Its near unpossible to row with the rudder any way but straight at a standstill (just started moving). Once you get moving, then you can turn. But turning slows you, so try to go in straight lines to row efficiently (such as it is). Also the controls are reversed in reverse, like a car.
Its possible to smack your boat with a weapon to get it moving, hit the mast facing where you want to go. This is not the best idea unless really, really stuck.

Tacking is a critical skill. To say it another way, its a vector zero sum game, like in physics. You go 100 feet left and 25 feet forward, then turn and go 100 feet right and 25 feet forward, then reverse it and go 100 left/25 forward.. and again... now you are 100 feet forward and in the same place relatively left and right... you only get a little bit of the component you in the direction you wanted to go, but its a lot faster than rowing against the wind if you have the space to do it. It wont work in small rivers.