You will need a beach towel, a water bucket, a large brush, cisors, a strong stappler, and of course, a canvas and watercolor.

Place the painted side face down on the towel, wet long enough and allover untill the corners are easily turned. The reason for the towel is to prevent the water to reach the painted surface.

Take your framed linen and put it ,cloth on the back of the paper (wet), turn the 2 longest sides and stapple them. Do not pull on the paper, it is fragile because it is wet, it could tear.
Do not use any glue, the paper will move freely as it dries.

Then, turn and tuck the end like if you were wraping a gift, stapple. Do all cornors like this. Cut the exces lenght.

Stapple all sides the same, at every inch because the paper will try to shrink in drying.

I love the finished product because it is presents itself very nicely with the scene going around the sides. The tickness of the canvas will also protect from wear and tear.
Please do not use any glue, the stapples will do the job, and you can always unstapple and wet it to flatten it.

When the paper is very dry and thight, spray the final mat varnish for dry mediums, such as crayons and pastels. Spray 2 to 3 coats at at least 1' distance, outdoor, with intervals of an hour.

You can hang your painting just like that or put it in a "floating" frame, it gives the impression it is floating because it is fastened from the back.