I'm not sure how your fabric came detached from the trailer; there's a piece of plastic in a steam that's retained by the sleeve on the trailer. I would carefully inspect the sleeve to make sure it has not been spread out so as to lose some of its ability to retain the fabric, which is under some significant tension when fully extended.
We put the fabric on the trailer w/ two people, but it does take a couple of ladders. If you can get one more helper, you don't need to remove the fabric from the roll, which is nice.
The instructions from zipdee are well worth reading in detail:
Installations and Replacements
You may wish to look at our blog, where webspinner describes her sewing of a new awning to replace PO's previous replacement.