Step 11: B) Pedal Control: Do the plumbing
Now assemble the elbows, pipes and valve. Wrap each set of threads with Teflon tape before threading it in. It's easiest to tighten all the pieces together before connecting to the wall, but you might thread them into the wall loosely just to be sure everything fits together the way you want. Don't forget the trim ring. (You can use the old one.) Tighten well--not only to prevent leaks, but also to make sure that it will stay together when you pull on the valve with the pedal.
When finally tighten the assembly into the wall, it might get tight at a different final angle than you want. If that happens, you can adjust by adding more Teflon tape so that it gets tight sooner.
You can check that it works now, but without a pedal, it's not very convenient for showering!