From bars 1-14, all chords are in E form, or based on 
the E chords, as you'll probably notice.  From bars 
16-30, all chords are in A form, or based on the open A 
chords.  On the chords starting on G7 and Gm7, the 
notes on the second string are optional.  You could 
simply bar that string.  As for the chords starting on Cm7 
(in A form), the top note is optional too.  You could bar 
it if you want.  Hence the word optional.  Starting on 
measure 32, I gave you some exercises to practice 
switching between forms, but you should not try them 
until you memorize everything else.  If you haven't 
memorized everything, you're just playing what I 
tabbed, not exercising your knowledge.  After all, that's 
the reason you downloaded this, isn't it?  Under the first 
one, I wrote what form it's in.  They won't sound too 
good the first few times, believe me, and they will 
probably hurt your fingers, but keep at it! Whether your 
trying to play barre chords, or crack a nut, the key is 
persistence.  E-mail me any questions...