To dock a bike you need to push the bike back into the docking point at a station. We find the best way to do this is to put your hand on the saddle to help you to push it in.
Watch Matthew in the video below, show you how:
If you have trouble locking the bike it is usually because the spokes on the front wheel are in the way of the lock. You can solve this by wiggling the front wheel to nudge the spokes out of the way.