How can I adjust the truss rod on my guitar to either loosen or tighten it?

To adjust the truss rod on your guitar to either loosen or tighten it, locate the truss rod adjustment nut usually at the headstock of the guitar. Use an appropriate tool, such as an Allen wrench, to turn the nut clockwise to tighten the truss rod and counter-clockwise to loosen it. Make small adjustments and check the neck relief to ensure proper alignment.