Intro:
G|---------------------------------------------------------------------|
D|---------------------------------------------------------------------|
A|----------------3---------------3---------------3--33-----------3--33|
E|----------3---5-----------3---5-----------3---5-----------3---5------|

After that, just play this over and over on the verses:

G|--------------------------------|
D|--------------------------------|
A|------3--3--3--3------3--3--3--3|
E|3---5-----------3---5-----------|

Choruses:
[ Tab from: https://www.guitartabs.cc/tabs/c/chicago/im_a_man_btab.html ]
G|----------------------------------------------------------------|
D|2-2-2-2-2-2-2-2-0-0-0-0-----------------------------------------|
A|------------------------4-4-4-4-3--3--3--3------3--3--3--3------|
E|------------------------------------------3---5-----------3---5-|

G|----------------------------------------------------------------|
D|2-2-2-2-2-2-2-2-0-0-0-0-----------------------------------------|
A|------------------------4-4-4-4-3--3--3--3------3--3--3--3------|
E|------------------------------------------3---5-----------3---5-|