You are eligible to apply for B.Ed after your graduation degree. The eligibility criteria for B.Ed is that you should have minimum of 45% marks in your qualifying exam, and you should be at least 19 years of age (most universities do not have a maximum age limit). Admission criteria to B.Ed courses varies, however most universities admit candidates based on a Common Entrance Test. If you are interested in teaching Secondary and Senior Secondary classes, then you might also want to get a post graduate degree either before or after the B.Ed.
CET forms are available till 24th may 2012.