To use your tapering jig, adjust the angle of the jig and tighten the wing nut. Then, position the board to be tapered firmly against the left side of the jig, with the end of the board against the lip at the bottom end of the jig (as shown in the image above).
Next, place the right-hand side of the jig against your table saw fence, then adjust the position of your fence so that you're cutting the taper at the desired width.
Hold the board against the jig and the jig against the fence and slide the entire apparatus through your saw blade. You should end up with a consistent, cleanly tapered board!