Thank you for your tip Darkstarlep!
That's already a big help! Only one thing, did you mean random heroic dungeon finder... if so, I'm not having much luck. They always fall apart.
For example: I just did one today and it failed very quickly with 2 people leaving on us and there was a rock bug that attacks whoever cast healing spell... and that was me.
So we ended up running out and party has been disbanded.
So far, it is not very encouraging..
Well in this case, I think I'll try raiding with guild!