The second position of the major scale begins it's pattern on the second note of the scale. So, if you were playing a G major scale in second position, the bottom note in the pattern would be "A" - two frets up from the root of the scale. This is actually much easier to hear than it is to explain.
Grab your guitar
Now, try playing the third fret on the sixth string of the guitar (the note G) with your first finger. Next, slide that finger up to the fifth fret, and play the pattern shown here. Play the scale forwards and backwards, staying in position throughout, using your fourth (pinky) finger to stretch. When you return to the fifth fret on the sixth string, slide your finger down again to play the note on the third fret.
Could you hear what happened? You just played a G major scale, which you'd normally play using the pattern outlined on the previous page. This time, however, you played the major scale two frets up, using a different scale pattern.
This is the concept we'll apply in the following steps to the rest of the positions of the major scale. The goal when complete is to be able to play a single major scale all over the fretboard.