Guitar 3 is the same melody / notes as Guitar 2, except for the fact that everything is played one octave higher.

So just like Guitar 2 the notes are:

During the C5 backing chord: F E E (hold) E F G F E D
During the Bb5 backing chord: E F F (hold)
During the Ab5 backing chord: Slide to D C C (hold)
During the Bb5 backing chord: Eb D D (hold)

(repeat)

During the ending G5 / C5 chords, the melody plays C B B (hold) and C (apply vibrato).

So this time everything is played up around frets 12 and 13 on the high strings. If you've read the Fundamentals (in the Theory section), you should know what Octaves are...but here's a quick synopsis:

There are only 12 notes, however they occur more than once - in higher or lower registers. So you can have a Very low C note, a low C note, a 'middle' C note, a high C note and so on. These divisions are called registers. So a low C is one register below a middle C. They are technically the same note (they share the same tone) except one is higher sounding than the other. We say these 2 notes are an 'octave' apart, rather than talking about registers. This makes more sense later when learning about scale construction.

In this case, we are playing exactly the same melody, in a higher register than last time. The effect is to thicken the sound of the melody. This is a very common thing to do when recording guitar layers. It adds depth to the sound!

If you can already play Guitar 2, then this Guitar 3 ActionTab shouldn't take you long to get right! Next we look at the last guitar - Guitar 4