Is need to file income tax returns

we registar one educational society in Hyderabad 1993- 1994

in the name of Vikas Siskha Samithi, 

Under this society we have 4 colleges

our turnver each college 15,00,000/-

we are not filing income tax returns is need to file income tax retuns and is there any exemptions on educational institutes.

we not apply for any exempetions from income tax department.

1. Is any exemption is applicable. 

2. How to get exemption cetificate.