I figured this out by trial and error. Mostly Error. I have a canopy frame that I want to make a greenhouse out of, but there is where the error comes in. I also have a book on self-watering garden that has something similar to these.
1st take some 1/2" PVCor CVPC, 10 foot lengths- 2each
then fold them over as in the pic, anchoring them to your raised beds or find some spikes that they will fit in. I prefer anchoring buy getting 1/2 " pipe hangers, and securing them to the sides of my raised beds. You might want to wrap the top of the pvc with duct tape to keep them from sliding-
Get a giant clear plastic bag and slip it over the frame. You should be able to find big plastic bags at most hoome imporvement stores.
Remember to anchor down the bag. Youcan use bricks, rocks. I used my trusty staple gun, and cut a slit to open for access and ventilation. I keep the slit closed with some spring clamps.