help with option trading

I would like to buy some shares in a company who's share price I think is overpriced and I think will fall in the future.

I have done some research and I am under the impression I want to buy a PUT option?

How do I buy a PUT option? I have a BellDirect share trading account, am I able to buy/sell options on this trdaing account? Or do I need a seperate account?

Any recommendations?

All help appreciiated! Thanks