LARGE Section Of Drywall Paper Peeled Off While Removing Water Damaged Wallpaper, How Do I Fix It?

I have started removing old wallpaper from a bathroom, there has been water damage along the bottom of the walls which has caused the drywall paper to completely come off in a big chunk. You can see in the picture that it is loose on the left and right side also. I cannot seem to find instructions on how to fix... show more I have started removing old wallpaper from a bathroom, there has been water damage along the bottom of the walls which has caused the drywall paper to completely come off in a big chunk. You can see in the picture that it is loose on the left and right side also.
I cannot seem to find instructions on how to fix this particular problem, where there is no actual paper left. (All I have seen is how to patch gouges.)
So if anyone can give me instructions and a supplies list or find a link or video, that would be awesome!
Thanks for your help
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