What will be the correct passive of - 'I told them the secret of my success'?

• Active voice কে Passive voice এ রূপান্তরের নিয়ম:
- Active Voice এর object‌ টি Passive voice এর subject হয় - 
- Tense অনুযায়ী Auxiliary verb -
- মূল verb এর past participle -
- Active voice এর subject টি Passive voice এর object হয় -
- তার পূর্বে Preposition (By, with, at, to, in) বসে।
Active Voice: I told them the secret of my success.
Passive Voice: They were told the secret of my success by me.

সূত্র: Advanced Learners Communicative English Grammar and Composition (For Class 9-10).