I gather two things from your question:
1. You are genuinely concerned about this cause; and
2. You don't want to engage a lawyer.
Well if that's the case, I would suggest you prepare a detailed dossier on the issue, explaining how it will cause harm or loss of livelihood. And file it with a cover letter with the office of the Chief Justice of the Madras High court. Asking him/her to take super Moto cognisance.
If your case is genuine and supported by material evidence, I am sure the courts will take action.
If you're keen to file a PIL, either engage a lawyer or refer to some books on the subject by eminent authors. The books are available in several online bookstores. If this helps you figure out both the law and procedure of PIL's, great.