Do I need to send the documents of OBC with IIT JEE form??? Which other documents are required???

Yes, you do need to send the documents of OBC with IIT JEE form, following documents are also required with the application form:

Date of Birth

Class 10 certificate

Class 12 certificate

Your signature in JPEG format

Passport size photograph in JPEG format

Category/Sub-Category certificate if applicable

Year of first attempt in JEE (Advanced) if applicable

Important dates
Admit card available from: March 1, 2014
JEE Main 2014 Paper Based Exam (Paper 1): April 6, 2014 - Time Slot 9.30 am to 12.30 pm
JEE Main 2014 Paper Based Exam (Paper 2): April 6, 2014 - Time Slot 2 pm to 5 pm
JEE Main 2014 Computer Based Test will be held on April 9, 11, 12 and 19, 2014
JEE Main 2014 Exam Results are expected to be declared on May 3, 2014
Declaration of All India Ranks: July 7, 2014