You can create characters until you run out of character slots (buy more via cash shop tickets or during promo events with In game currency).
Once you're in the game world you can enter character editor but you either need to use a character edit ticket or have a value pack active to "apply" the changes. You can save changes to "save slots".
Value Packs are pretty common in the in game market but are also hotly contested. It is has been a while since I played but I think there were some changes to the market to make pre-ordering value packs possible. Maybe
Biestmann can chime in.
The game also awards value packs sometimes. Log in bonuses, events etc.