How to change composition to a paper in the wind

You cannot really bend stuff in AE. There's of course a bend parameter when you set the comp renderer to Cinema 4D and you can use e.g. the Page Turn effect to create the ilusion in 2D, but if you need it to be more realistic you will have to use a 3D program.

Mylenium

In the simplest case you use it as a 3D layer in a parent comp and animate position and rotation. Otherwise you realyl have to be much more specific about what you are actually trying to achieve.

Mylenium