Simply explore the world and if you find any NPCs with a yellow exclamation point floating over their heads, right-click on the NPC and a quest menu will pop up explaining the quest. At the bottom of the window you will have the option to accept or decline the quest. If you abandon a quest you already have accepted, you can go back to the appropriate quest NPC to regain that quest again.

If your character level is significantly higher than the level of the quest, the NPC may not display the yellow exclamation point, but you will still be able to interact with the NPC and obtain the quest. The higher your character level in relation to the quest level, the lower your experience reward may be.

A quest line is a group of quests that can only be completed in sequence, as they explain or expand on a plot that a player is following. The quests generally start simple and can build to very complex or serious quests that will span far into a characters life as they grow in experience.

There is a function called "Share Quest" which allows a player to give an active quest they currently have to another player in their party. This feature is limited to certain quests, and it will not allow a player to bypass earlier portions of a quest line. Its main purpose is to allow party members to easily maintain and share the quests they are currently working on without one member having to run back to town to grab the quest, which delays the rest of the party. The "Share Quest" button can be found at the bottom of the active quest log window.

If you die and do not release your spirit before the mob dies, you will still get credit for the kill. If you do release, you will not get credit for your group slaying it and you will have to kill him again.