ofo (spelled with two lower case o's) is offering rides until January 31 (Wednesday) for free.
Just download the ofo app and open it to find a bike near you. When you're at the bike, tape "unlock" and scan the barcode to unlock the bike and go for a ride.
At your destination, park the park and manually lock it.
Unlike B-cycle, you don't have to find a docking station. You just leave the bike at your destination and wait for someone else to take it and use it.