I'm playing as Guile & every move on my move list says 'Charge' before it.... WTF does that mean? I'm an SF newb.
EDIT: Does it mean I have to walk that direction for 3 seconds?

Hold the pad or stick in that direction for a couple of seconds.  You kind of have to learn the timing yourself.

On the left side, hold LEFT or DOWN-LEFT for about 1.5 to 2 seconds (it's usually/supposed to be something like 55 frames, but these can change per character) and then do the move.  RIGHT for the opposite side. 

DOWN is hold down for 1.5 to 2 seconds. 

So, for Guile's Sonic Boom, hold LEFT for 1.5 to 2 seconds then RIGHT + Punch. 

If you want read about Charges in super technical jargen, then here you go!: http://sonichurricane.com/articles/sfcharge.html

What if the move starts with a quarter turn or something, how do I charge that?