How to program servos?

Hey I’ve been trying to make a character for a long time and servos seem like the way to go, but how do I use Arduino for that? Do I use Arduino to make the circuit and then connect that to Bottango to program it? What’s the best circuit board to buy because I want to program a lot of movements? What the heck is a potentiometer? I want to know the right stuff to get and what to do with it so that I can teach my self the rest when the time comes.