I am assuming you have a basic knowledge of music theory.
If you don't here's the short version of what you need to know.
Sharps and flats are between the natural notes and they are called either a sharp or a flat according to which way you are headed on the fretboard.
For example if I am headed towards A backwards from B It would be a Bb (flat).So it would be B, B flat and then A.
If I was headed forward towards B from A it would be a A# (sharp). So it would be A, A sharp, B.
So in this step fill mentally fill in the blanks.
A --- A#/Bb --- BC --- C#/Db --- D --- EF --- F#/Gb --- G
If you have been following the fretboard chart system you have may have noticed that all we have learned are the natural notes and not the sharps and the flats.
Guitar fretboard memorization system - step 6
Instructions for step 6:
This is where you come in.
In between the notes go ahead and fill them in using your imagination.
Memorize each chart referring to your guitar as you work along. Using a tuner if you have it for easy reverence and to check your accuracy.
Get a feel for the spacing in between the natural notes.
That's all there is to it.