Insert the hex key into the truss rod bolt where the neck meets the head-stock and adjust the truss rod tension as needed.
Tightening towards the D-string (clockwise) helps to bend the center of the neck toward the string and loosening towards the G-string (counterclockwise) lets the strings pull the head-stock downwards.
Be sure to make small adjustments, as overtightening the truss rod can lead to the neck of your guitar snapping under load!
In the intro you talk about tightening the truss rod to relieve fret buzz. Tightening the truss rod will produce more back-bow and result in more fret buzz. Also, how can you have looser strings and still have the same "tuning"? Strings need a certain tension for a certain length to produce the pitch you are after.