[mlizzy]

Okay, I “think” I understand this. What would I do about the sides of the lean-to?

[ApplegateRanch]

Use a sheet long enough that the front-bottom will fold back to the fence, while the top will drape down to the ground. The ends, next to the fence, running down to the ground get the same treatment as the top. Fold as necessary at the ground level, and weight it down all around the ends and front.

This is the closest I could find, which doesn't have ends (ignore the right half of the picture). Seems everyone wants fancy and expensive these days.