string saddle movements/ adjustments (part A) are necessary only if the notes after the 12th fret (tuning) are off, after you've tuned your guitar. there're plenty of references online should you decide to embark on this rectification. don't worry, adjustments to A & B won't render your guitar out of order should anything goes amiss.
refer to the pic below, the truss rod tip of an LP type guitar is beneath the bell-like cover immediately after the nut. adjust your truss rod only if you know what you are doing, otherwise, refer to an experienced/ knowledgeable person.
**just a reminder- such technical discussions are to be addressed over at the 'How To' thread 8)