Theres an event going on until February 4th in which you can get prizes for doing certain things in-game.

The things you need to do are :

1. Create a character
2. Visit 7 events (not sure what this means)
3. Something about skills (you'll get it no matter what)
4. Join a guild
5. Impossible for us to do so don't worry about it
6. Summon the Dragon (this one will give you the mount)
7. Win 10 ranked battles

You can see the prizes and how many of them you've done here: http://dbo.netmarble.net/Event/2010/20100111_7Ball/

You don't need to do all of them or in any order. To claim your reward: click the button underneath the prize on the website above. You can then pick it up in-game by clicking on the capsule icon at the bottom right hand corner of the screen.