I have an image of a 2D image ( sky and cloud). I want to use it in a 3D scene.To cover the back I would need to paste this image on a round surface so you dont see the corners of the image when moving the camera.
Can you do this in After Effects cs 5.5?
Yes. Both plugins respond to the After Effects camera in 3D space, so you can position your camera "inside" the Sphere or Cylinder. But note Mylenium's advice to set it to render "Inside Only".
Alternately, you can break your background into segments and orient them so you have a series of flat planes instead of a true curve, which often works well enough.
Or, investigate Trapcode Horizon.