Yeah, I realize this must sound like a total noob question, but I'm unsure about it. I've only been playing a short while, and I'm curious.

For example, a couple of people and myself where trying to do the Stockades in SW and we were getting owned. We asked for help from a lvl 60 player and he said we chose the really hard instance.

How do you choose instances?

Thank you for not making fun of me in advance :P