What was the final result of the case before the Joint Divisional Registrar and the Minister for Co-operation. Were you exonerated of all the complaints against you? Had the members used the word "misappropriation" in their complaint only but also had otherwise brought it to the knowledge of the general public?
Did they give any reply to your letters demanding apology? If they had given you reply, had they maintained what they said was right? If they have not replied at all, just send a lawyer notice and that may do the trick.
You have not stated what exactly did you do. Was it illegal according to you? Making an illegal payment is also bad and can attract punishment. Whether illegal payment or misappropriation is worse will depend on facts and circumstances. Misappropriation generally means taking money under one's charge for one's own benefit. Illegal payment would mean giving illegal benefit to someone else. Whether one was oneself benefited from such illegal payment may not be readily apparent, the benefit of doubt always going to the person charged with such offense. It will be difficult to argue that you did something illegal but did not misappropriate, especially because the case was serious enough to go before the Joint Registrar and the Minister.
Now what exactly do you want from the members, an apology, cash compensation or jail for them under IPC 499 and 500?
If you want only an apology, they will readily give it, if the case proceeds to the extent of their being summoned to the court. If you want cash compensation, it will be expensive for you also without even knowing whether eventually you will get the compensation.
Getting them jailed will be really difficult. You can have the satisfaction of having harassed them. But you will be harassing yourself also in the process.
If you want to file a case the best thing to do, is to entrust the thing to a lawyer. But if you want to fight yourself without a lawyer, you go to the court having jurisdiction and ask the clerk there. You will have to draft the plaint yourself. You may have to pay court fees etc also