| It's a bit tricky to get the hang of everything. If you set the expression pedal to control the number of repeats (you should select the "dF" setting for the expression pedal), you can rock it to the toe position to make the number of repeats infinity, and rock it to the heel position to make the number of repeats close to zero. So if you play a riff and then rock the expression pedal to the toe position, the riff will loop. If you rock the pedal to the heel position, it will clear everything that's repeating.
The problem is that there isn't any tap tempo, so you have to set the delay time beforehand, and then get used to that tempo (which can be hard for the long delay times you will be using if you're looping). Also, in order to add a new phrase to the loop, you need to rock the pedal out of the toe position, play your riff, and then move back into the toe position.
Sorry for the long and confusing post. I'll clarify if you have any questions. | 
