Experience: You will obtain experience once you attack a monster. The more damage you do the more experience you will get. If you are in a team, you can also obtain experience when your teammate kills a monster. When your experience bar is full, you will level up.
Pick Up Items: Most monsters drop cash and/or items. Also, the players might drop items or money when they get killed. Move the mouse point over the items till it becomes a hand, click on the items on the ground to pick them up.
Tip: Combat in a team will get you more experience, and makes strong monsters easier to kill. You have to wait a while to pick up other player’s loot.