From the web site:
How it works
Enjoy your city! Baltimore Bike Share sets you free to explore Baltimore on two wheels.
Baltimore Bike Share is public transportation on your schedule. Grab a bike, go for a ride, give it back. You can pay for Bike Share by the month or by the trip, similar to MTA.
Become a Pass holder and use Bike Share at your convenience.
Walk to a station, choose your bike, and unlock it with your pass or the Baltimore Bike Share App.
Ride around the City in style.
Return the bike to any Baltimore Bike Share station.