You can charge a damage deposit by simply "requesting money" in the resolution center.
Be aware that this is not a sanctioned function of Airbnb, and may be subject to refund if the guest complains. So be sure the guest understands what it is and agrees to it.
We've found it delivers excellent results.
Also, realise that it's for damages, not because the guest was a bit messy or otherwise insulted you somehow. Always give the deposit back in full, preferably in cash, at checkout time if there's no damages. Otherwise, this will be stopped in fairly short order.