I think its probably just step one thats got you stumped, and it can be pretty hard to figure out. Heres what you do step by step for the stuff contained in step 1:
1. Create a new solid (he says to make it 30×30, but i think any size works)
2. Create 2 position keyframes. You should set them as far apart as you want the animation to last.
3. Select the 2 keyframes and then apply the wiggler, using the settings he shows.
4. Create a new solid the same size as your composition.
5. Use the pen tool to create a single mask point on this new solid.
6. Click on the position property of the original solid. This will select all the position keyframes on this solid. After applying the wiggler, there should be a lot of keyframes on it.
7. Copy the keyframes, and then paste them to the mask shape property of the2nd solid. This should create a nice curvey mask shape on that solid.
8. You can now delete the first solid, and proceed to step 2 of the tutorial.