Quests are tasks personally given to you by non-player characters, or NPCs.
To interact with an NPC, you would use the TALK command on him or her. Talking to NPCs that you see is a good idea! You never know what they might have for you.
Quests have a variety of requirements and there is no practical way to write a help file that covers all possibilities. Just remember to listen carefully to what the NPC tells you. They will often repeat information if you talk to them again.
As a roleplaying note, talking about quests is generally very out-of-character. For one thing, nobody talks that way -- if your dad told you to go down to the corner shop for a loaf of bread, would you tell everyone your dad had just given you a quest? Secondly, it makes very little sense for a person in the game world to require the same favor over and over again, so this means that the quests you've been given should be treated as a personal one-time task -- it does not make sense to talk ICly as if it is a repeatable task performed by everyone. This must simply be glossed over as a necessary conceit of a multiplayer roleplaying game.
For these reasons, and also so that everyone has an equal opportunity to enjoy figuring out their quests, it is against policy to share quest walkthroughs or puzzle solutions.
