Normally, there is a place to put a wrench on a pedal right next to the crank arm. If its not there, look on the other side of the crank arm for a hexagonal hole in which to use an allen wrench. There is always a way to unscrew the pedal from the crank arm!

Beware of jumping right in & taking the bottom bracket apart. Why do you want to do that? (I only ask because it sounds like you're new to this...)