scuola for dummies?

Do you mean the drawstring under the flap? If so, squeeze the two sides of the, what's that thing called, the thing hanging on the drawstring, then push it up towards the opening to tighten. Not sure if this helps.
 
If you mean the canvas strap:
1. Pull the bottom strap up through both loops;
2. Bend strap down and put it OVER the top loop and UNDER the bottom loop;
3. Pull tight;
4. Rock your scuola!