Place the straight edge ruler on top of the guitar frets. Look for any areas where the straight-edge does not make contact with the frets. These areas will need to be adjusted to straighten the guitar neck.
Loosen the tuning pegs on the top of the guitar neck to relieve the string tension by turning them counterclockwise. You don't need to remove the strings, just loosen them by turning the pegs one-half turn.
Turn the two bolts on the neck counterclockwise to loosen them. Turn them approximately two quarter turns. Start with the one furthest away from the peghead and turn the one closest to the peghead.
Pull up on the neck of the guitar and remove it to expose the truss rods inside the guitar neck.
Insert a flat-head screwdriver into the top truss rod and turn in one-eighth inch at a time until it is straight. Turn counterclockwise to make the neck relax and clockwise to pull the neck up. You can check the alignment by re-attaching the neck of the guitar.
Adjust all of the truss rods that were not aligned by using the procedure from step 5. Reattach the neck and check the alignment with the straight edge. If additional adjustment is needed, complete the procedure again.