How do I remove the windshield wiper arm on a 2007 Chevy Impala?

[David]

I was driving along the interstate, when my windshield wipers stopped working. You can hear the motor still run, but the wipers themselves don't move. I read somewhere that the arm needs replaced, or perhaps there's a rubber grommet that holds something on the motor that turns the wipers themselves. I wouldn't think it would be too difficult to change, but don't know how they're assembled. Do I need any special tools?

Thanks in advance