Nikon D5100 w/ SB-600 Speedlight (Off Camera Flash)?

Hi. I have been taking pictures for years but I'm new to using external flash. I have a Nikon D5100.Is there a way to use my SB-600 as a slave / off-camera flash, wirelessly? Also, is there a way to trigger the SB-600 off-camera, without using the built-in flash on my D5100 (because when I take portrait I stand fairly close to my subject, I want to put my SB-600 off-camera at the back of the subject to light up the hair color, but not using built-in flash to avoid the face from looking washed out).

One of the virtues of an entry-level DSLR, your D5100 does not have the necessary remote commander built into it to control the flash.

But you can buy a SU-800 which sits on your camera's hot shoe and does provide you with remote commander capability.

Or you can buy a SC-28/SC-29 flash cable if you don't mind wired.