You didn't mention what extension you're trying to import into, so I can't really give a very specific answer. In general, when JFBConnect is installed, profile plugins for any supported extensions should be installed automatically.
To enable, please go to your plugin manager and enable the plugins in the SocialProfiles group for extensions you want to import data into. You can configure the plugins from the JFBConnect -> Profiles area.
I hope that helps, but if you need anything else, just let us know as many details as you can.