In which case, your role in the dungeon will be to deal damage.
Carries less responsibility than the other two roles, but mistakes can still cause problems. Personally, I always try to:
- Be nice
- Try to understand that everyone has to learn (not going to be a problem for you yet, but all too easily forgotten it seems)
- Respect the loot system
- If people in there know what they're doing, listen to them
- Really goes back to #1, but try not to retaliate when you find someone that's not understanding. Not always easy, has always helped me keep calm
Personally, I will do a good amount of research on a role anyway before I group up. It's my responsibility as DPS to do as much damage as I can without pulling aggro from the tank. Also, if you have any utility spells (silence or decurse for example) be aware and use them if/when necessary.
It's a learning process, but ultimately (usually) rewarding.