These instructions show what you should see while looking in the mirror.
Begin by placing the center of your belt against your waist.
Wrap the belt around both sides, with the right side sitting on top.
Continue to wrap the belt around, keeping the end on the left side tucked underneath.
Cross the right side over the left.
Take the side on top and bring it up under both layers. Pull it tight.
At this point, you can check that both ends are roughly the same length, and adjust if needed.
Pull the bottom end across your body to the left, crossing the top end. This should form a small hole.
Reach through the hole, grabbing the top end. Pull it through and tighten the knot.
These images are based on a series taken (with permission) from http://www.nackordkarate.com/