A great way to learn the names of the notes on the fretboard is to start with just a few notes on a couple strings. We'll start with strings 5 and 6, as they are often used to identify Power Chords, Barre Chords, and Scale shapes. Here are the first three notes of the Music Alphabet;

We'll follow these notes with the last three notes of the Alphabet;

String 6: E F G

Adding D to complete the Music Alphabet

By adding D, we complete the Music Alphabet and now have all of the Natural notes.

Adding A on the 6th String and E on the 5th String (Octave)

Notes can be played in multiple places on the fretboard. Understanding this allows us to play in different areas of the neck, which can sometimes make things easier.

Sharps and Flats

Sharps and Flats are called Accidentals - they are the black keys on a piano, or the frets in-between the Natural notes on the guitar. They are called Accidentals because they have something added to their name (they are longer Natural). Every Accidental can have two names, a Flat name and a Sharp name. 

The correct names to use for Accidentals can be a little complicated - it has to do with the Key you are in and how scales are constructed. 

While we are getting used to finding Sharps and Flats, we will simplify things and say that; 

Sharps are higher in pitch, moving up the fretboard. 

Flats are lower in pitch, moving down the fretboard. 

(I know this is not always true - we will just use this as a guide for now, until we understand scales and keys better).

Here is the first exception to our "Sharps go up, Flats go down" rule; You might have wanted to call the chord in Bar three Gb, but F# makes more sense, from a theoretical perspective. As long as you can out the two names for an Accidental, you will be ok.

25 or 6 to 4 - Chicago

Half of the Notes

So far we have only looked at the 5th and 6th strings. The notes on the first string are the same as the 6th string, so by learning one, we automatically learn the other. This means that we have already learned 3 of the 6 strings, or 50% of the notes on the fretboard.

Using Octaves To Identify Notes On Other Strings

Octaves are pretty easy to locate on the guitar fretboard, you just move;

Up two strings, up two frets

You can see this illustrated in the diagrams below.

Before we discuss Octave shapes any further, we need to introduce the concept of "Time Zones".

When we use our Octave shape starting from string 4, we cross into a different time zone, which means we have to modify our pattern;

Up two strings, up three frets

You have to move up one extra fret on the 2nd string to compensate for the "one hour time difference").