Try to define your role in a group. There are basically 3 things a group needs every time: a tank, a healer and DPS. It's handy if DPS is capable of Crowd controlling to make an instance easier.
If you are looking for a group or making one yourself look for those 3 things and MAYBE prefer more crowd control capable classes over those that are less or not capable (like a retribution paladin has basically no CC just as a moonkin, atm). I'm not saying those classes won't work, are bad or something. But it might be better to keep their weaknesses in mind if you just start getting into "the group thing"
A hunter is there for DPS and laying traps for crowd control. That's what he's doing in PvE and PvP. With the difference that opposing players won't make it as easy business as mobs do.
And besides of all that, just take complains not to serious, but try to learn and improve.