Your hoop house frame looks much better constructed and has more poles than the cheap ones people have been buying as chicken runs, so you may not need any additional structure added to it. If you do, commonly people will use 1x4 or 1x3 lumber and install as purlins across the metal structure for more support backing, and attach the fencing to the wood. You can attach the wood to the pole structure with different methods - holes and metal zip ties/wire, plumber's strap/hanger tape and screws, metal brackets, etc.
48" HC is the common height people would use. If trying to install directly onto the tube structure without any additional supports, I'd likely consider going vertical orientation by going up and over the top. Probably overlap the seams by 1-3 rows of HC and either use hog ties, stainless zip ties, or sew it together with galvanized wire (I sewed my seams with wire for no loose edges). Frame in the end with some wood framing for a door, again the wood can be fastened to the pole structure with something like plumber's strapping.
Good luck!