Follow @d8veh advice and check out how FT build their wings.
Also, try to be more specific with your information so that we can help. A flat bottomed wing thing that won't fly could apply to most pieces of furniture in my house, which are flat bottomed.
The pics are useful so that we can see what you made - all you need to do is tell us what size the wing is (span, chord), what kind of plane did you try to fly it in, what was the overall weight of the plane, what power system did you use, etc, etc.
Sounds like you are not using the same foam the rest of us are using. The methods we use may not work on your foam. It would be helpful if you could tell us what foam you are using. Please describe it in the best way you can.
Our foam is fairly flexible, it gets strength from the paper. If you remove the paper form one side, the foam on the inside of the curve will crush, you can form a very tight curve, like Ed did in the Armin wing. Not all foams are that flexible, some would crack if you bent them that much, even with the paper on one side. With a less flexible foam, try scoring it where you want the bend. Like FT wing does.
If you foam is not at all bendable you should consider a KF airfoil. They are easy to build, I've had excellent results with the KF-2 & KF-3. It's just a mater of getting the dimensions about right.
Regarding the paper, try using a ordinary white paper glue, thinned with water 50-50. You want it thin enough to paint on the foam and the paper. It will make the paper wet which will help it lay down smoothly and get good contact with the foam. It will take time to dry. Regarding hot glue. It looks like you are working with glue that is not hot enough. You may have a low temp gun or have too much area to cover. The glue is cooling too much before you can get it spread. There is nothing worse than working with cold glue.
We need to experiment with different methods to see what will work for your foam. But you will need to give us feed back, you will need to be our eyes and describe what you see. Help us help you, right now we are all guessing.