Watch the The E chord online guitar lesson by David Hamburger from Blues Guitar For Beginners
With every song, the order of the chords and how long you play each one adds up to something called the form. Pop tunes can have a fairly elaborate form - a few verses with a distinctly different chorus, maybe broken up by a bridge later in the song. Many blues tunes, on the other hand, like this one, consist of just one fairly short cycle of chords, repeated throughout the song.
>>Form in Music