Okay, the top bill in this image shows the
"half-top-to-bottom"
fold.
In this picture, the top edge of the front face of the bill is in the
middle/right of the picture. It is (approximately) horizontal.
The half-top-to-bottom fold is also horizontal in this picture, but is (mostly) obscured by two other folds.
Using the half-top-to-bottom's crease, fold the bottom right corner (as seen in this picture).
This will cause the lower half of the diagonal fold shown at the bottom
of this picture to approximately meet the other diagonal on the right
side.
Imagine that the following text is a stylized diagram of the previous picture:
. \ . \ . \-------------------. . \ / . \ / . \ / fold line --------> . \ / <-------- fold line . \ / . \ / .
If you get that one fold, it should now look like this:
. \ . \ . \-------------------. . \ .\ / . \ . \ / . . \ / --------------- <---- Fold was here
(Okay, it's really hard to draw diagonals in ASCII.)
Anyway, I know that's not necessarily a whole lot clearer, but without the ability to take more pictures at the moment, that's about the best I can do...