How do you connect a generator at the electric meter?

You don't. The electric meter is not your property, it is the property of the company that supplies the electric.

A generator gets connected to the main panel if you want it to supply power to the house if the power that comes from your supplier is cut off.
This is dangerous work, working inside the panel and should be done by a qualified electrician and not by a do it yourself-er. So no one should answer this question as they wouldn't want to be responsible for killing someone to save them a few dollars.