Excerpt:
The Major Scale is the foundation for nearly all of what we know as Western Harmony. It's construction allows us to understand how nearly all rock music goes together, and our understanding of it's workings is an essential part of everyone's musical education. The construction of the major scale follows the same formula every time. Starting from your root note (the key you are playing in), you move up the following pattern:

1    2    3    4    5    6     7
  W - W - H - W - W - W - H

C - D - E  - F  - G - A  - B  - C
G - A - B  - C  - D - E  - F# - G
D - E - F# - G  - A - B  - C# - D
A - B - C# - D  - E - F# - G# - A
F - G - A  - Bb - C - D  - E  - F

W = Whole Step (2 frets on the guitar)
H = Half Step (1 fret on the guitar)
- always ascending up the guitar in pitch

Notice the numbering...