Scenarios

I got a quest from the daily quests to go help Varian in a scenario but I don't know what they are?

I usually stick with questing and pet battles but I want to see the story. Are these safe to go to without being yelled at? I've never done any dungeons because I'm scared and I'm not a fast learner.

Do they have other people in them or is it just like questing? And, if so, are they stressful or anything? I thought that the beginning of it where you fight with the king was fun so I'm looking forward to it if I can! :x

Thank you :)