Scales are about the most important thing you can learn. Everything is built on them. Chords, lead lines, everything.
This might get long, as I'm going to start way in the beginning. For right now, lets not worry about things like key signature or any theory items at all. Lets just look at your fretboard. We will only work until the 12th fret. Go get your guitar, print this out, and read on.
You have six strings. E A D G B e. That will provide five notes when played open, as you get 'E' twice.
Underneath each string are frets. Start with an open string. Pluck a tone. Then play the 1st fret on the same string, and pluck a tone. Do this all the way down the neck one fret at a time on one string until you reach the 12th fret.
What you have just played is called a "chromatic scale." It is composed of "half steps" or "half tones" between the notes. There are 12 notes in the chromatic scale (which is why you stopped on the 12th fret). On the guitar, the difference between one fret and another is a half step. This difference is referred to as "the interval."
A scale is composed of ordered notes played at various intervals. The first note you play is called the root, or the tonic note, and names the scales key. So if you played that last scale on the 'E' string, you played an 'E chromatic scale.' If you were to start that scale at the 1st fret on the 'E' string, and play to the 13th fret, you would have played an 'F chromatic scale.'
The "major scale" (which you're going to want to learn) is composed of the following intervals.
Root. Whole step, whole, half, whole, whole, whole, half.
So, using the same string you played the chromatic scale on, play the following frets, and see how they relate to the whole step/half step pattern.
Open (root), 2nd(whole), 4th(whole), 5th (half), 7th(whole), 9th(whole), 11th(whole), 12th(half).
Congratulations. Major scale. Different scales will have different step patterns between the notes, and may even have more or fewer notes. Pentatonic scales are made up of only five notes, for example.
So thats what a scale is. If you take the knowledge that they are made up of various step patterns, and that they will start on a root note, your scale book might make a bit more sense.
The practical reality is that they are made up of patterns, and so that pattern can apply directly to the fretboard. The fretting pattern you would play for one scale is pretty much the same pattern you would play for the same scale in any key, for the most part. Look for that in your book, and it will probably make a lot more sense.
Good luck, and practice every day.
