Re: free wheel crank
on left side of bike,a chain goes from the engine to a small sprocket on a jackshaft pole axle and the other side of it goes to a small sprocket, and from there a chain goes down to a freewheel crank sprocket: it replaces your peddal axle which will now have 2 sprockets one for the peddal chain and one with a freewheel kinda like a one that you would see on the rear peddal side of a bike and that would connect to the small sprocket on the jackshaft axle above.
the jackshaft axle pole with 2 small sprockets mounts to the straight frame pole under seat and connectes to rear engine mount. and the freewheel axle and peddals go where your old ones were. the freewheel keeps your peddals from turning when you are running the engine and chain to the rear wheel.