How Do You Detach The Rear Lens Body Cap

To detach a rear cap of a photographic camera lens, hold the lens from a part that it's not rotating -- usually near the back of it -- with one hand, steadily, and with your other hand gently turn the cap either clockwise, for e.g. Nikon cameras, or counter-clockwise, for e.g. Canon, or Panasonic cameras; there are usually marks etched on the cap, to tell you to which direction you must turn it in order to take it off. There are also marks on both the cap and the lens, usually in the form of a dot, which you must align in order to attach the cap to the lens (the same is true for the camera bodies).

To detach a camera body cap, follow a procedure similar to the above described.

As a precaution, take these steps over a soft, cushioning surface (a bed or sofa will do just fine), in order to avoid mishaps.

You may find helpful the info and photos @

How to Attach a Lens to the Nikon DSLR
http://www.wikihow.com/Attach-a-Lens-to-the-Nikon-DSLR

and, of course, your camera (and lens) manual!