Lay your white Bristol board on a flat surface and make sure all white lights in the room are turned on. Any additional light will only help even out the wash of white surrounding the jewelry in the light tent. Make sure to place the jewelry on the Bristol board prior to shooting.
Position your camera on a tripod a foot away from the Bristol board, focus your lens and turn on your light attachment.
Drape the white muslin over the camera and extend it to the Bristol board, completely covering the jewelry object. If the muslin is less than pure white, the object won't appear as vibrant when photographed, so be sure the muslin is pure white.
Tape the muslin onto the top of the camera. Make sure the muslin is positioned properly over the camera and jewelry, with none of the outside area around the Bristol board showing.
Take a test photo with the muslin in place to be sure your light tent is working to your satisfaction. If you find the tent too dark, add an overhead light directly over the jewelry, covered by the muslin to finish your jewelry light box.