I'm sorry if I don't quite understand how the antenna won't plug into your converter. The converter and antenna both should have an "F" type connector, and the connector from the rabbit ears should screw onto the connector on your converter. Unless you have older rabbit ears with 2-lead 300 ohm flat cable coming out of the rabbit ears. In that case, you would need a matching transformer:
Attach your antenna to the screws and plug into your converter - they're pretty cheap, a few dollars, and you can find them at Walmart, Kmart, or most hardware stores.
The only other thing I can think of is that the connector on your rabbit ears is damaged and won't fit.
You'll want to make sure your rabbit ears have a "LOOP" as well as the 2 long "EARS", or you won't get any of your UHF channels - Most TV stations broadcast in the UHF now.