To register for a public bike card, you'll need to provide your passport and place a deposit into your account. I believe the deposit is about 200rmb for 1 year, but don't quote me on that.
After successfully registering, you'll be able to use a public bike free of charge for an hour. And, if you wish to use the bike again, simply place it back in a rack before the hour ends and take it out again. Furthermore, failure to place the bike back in time will result in money being deducted from your account. You may retrieve the remaining funds on your bike card at the end of the year, as well. Here's the process of taking a bike:
2. ALWAYS CHECK the bike's brakes, tires, bell, and seat before releasing it.
3. Place and hold your public bike membership card on top of the card reader. Wait for the to say, "Qing qu che" (Ching chew chuah, if that helps). The bike will release.
Again, after it's release, you are free to use the bike for 1 hour. You may return the bike to any rack located around the city. To return it, simply put it back into the rack, wait for it to lock, then place and hold your card on the card reader until it says "Xie-xie." If you wish to use the bike again, you may do so using the same release process.