Watch the Thumbs Up online guitar lesson by Brad Carlton from Chord Studies: Evolving Progressions Vol. 1

This is a I - vi - â™­VII - V progression in E. Notice how the thumb changes positions throughout, helping you throughout the changes. For the open chords your thumb can hang out comfortably in a relaxed position, but when you play the chords that involve barreing, you'll need to move it towards the back of the neck.