This page explains everything to do with Quest Points
What are Quest Points?
Quest Points are an alternative to ingame currency. They are not tradeable but they can be used to buy items from the Quest shop (accessible by going to /warp Quests and selecting the Eye of Ender titled 'Quest Point Shop').
How do I acquire Quest Points?
Quest Points can currently only be earned in two ways. You can earn them by completing Quests (see here) or through Mob Arena (see here).