Start with a dollar.
Fold the top corner down like this.
Unfold and fold down the other corner like so.
Now unfold and fold the corners down like this.
You should have something like this now.
Now fold the corners up like this.
Unfold slightly and make a squash fold.
Now fold down the top corner just above the midpoint of the two squares. Make sure the crease for this is sharp because the next step will be tricky.
This part is a little tricky so have patience if you're a beginner. Unfold the previous fold and the unfold a bit more to sink down that tip corner. Watch the video closely if you're confused.
Once this is done, fold the edges of the two squares like so.
Now make some more squash folds.
You should have something like this. And in the interest of time, repeat all steps for the other side of the dollar. You may proceed to the next step once you have done so.
It should look like this.
Now you will fold this in half.
And unfold partially like this.
Fold that top corner down behind.
Turn over and flip the top part down until it meets the bottom.
Now you will fold this bottom part and tuck it underneath so it will hold it together.
You are now done. If you want, you can lay something heavy on it or stick it in a heavy book for a while until it becomes flat.
This is the final result. :D