Of course you can, just pile in.
Seriously, I met a dude last night in game that said he wasn't ready for a specific one of the new uprisings because he needed to do some research first... c'mon, just play the game! It is only a game. Work it out together.
However, just let your team-mates know that you are brand new to it. I have been in and led many operations both in guild and pug and never seen anyone turned away - however, if you say you know something and you don't, or say you can do X Y or Z and cannot and have no knowledge of how or even what those things are... well... I cannot help you there.
And I will say that completing some content, regardless of the difficulty, with no guide and working it out yourselves is one of the more enjoyable and bonding things you can do in game, whether its your first crack at a SM boss or your nth crack at the HM version.