The D7000 already has a bracketing button (shown in the image above) on the left side, above the lens mount. While keeping this button pressed, you can rotate the front and rear command dials to configure the exposure value (± EV) and the no. of frames.
You can then switch the shutter release to CL (continuous low) or CH (continuous lowhigh) to take multiple bracketed shots for an HDR (if that's the intent).
Hope this helps.