duct tape!! or any strong wide tape will work. good luck

The only problem with duct tape is that it leaves a nasty residue and over time when it gets wet, it adhesive quality diminishes. I found that if you can remove the canopy and clean it well where it is fraying, an iron on canvass patch does wonders and will hold for years even in the rain because they are meant for garments that go through the wash. Get the larger ones that say heavy duty on the package and it will hold fine. Iron it on from behind and make sure you get all of the frayed area covered and you are good to go.