Where can i find free critical essay on this novel "The Autobiography of an Ex-Colored Man" ?

Your junior college or state college libraries have computers with access to literally thousands of acedmic journals with critical essays for your perusal. There is no charge, access is free- send them to your e-mail and print them out at your leisure. If you're not able to physically travel to these libraries, contact them by phone and see if there is some kind of online access available for non-students. There may be. Also try your local library for online access to academic journals.