The max level will be 50.
Level 1: No exp
Level 2: 500 exp
Level 3: 1500 exp
Level 4: 2500 Exp
Level 5: 3500 exp
And so on till level 50. Increments will go up by 1000 exp each level.
Leveling your character requires you to kill enemies. Be they other people (PvP) or "Mobs" (humanoid, creatures, monsters, etc). You can also gain exp by defeating "Bosses" and "Epic Bosses", and these will grant double the exp as well as give you items, weapons and armor.