The currency used in this server is "Yen". The easiest way to earn Yen is by mining ores and selling them.
You can also earn yen buy using chestshop (which you can only build with apprentice or higher ranks).
You can also check your balance with either hitting "TAB" key or following commands:
| /bal, /balance, or /money
Simply type: /menu and you will be able to access the Admin Shop.