questions about raiding

hi, i am a fairly new player and I'm wondering if people do the raids from vanilla? or just get to level 80 and only do raids at level cap? I'm also wondering if there are guilds that are willing to help newer players who are interested in raiding. I've fallen in love with this game and would like to see all the content, but finding out where to start while being around people who've been playing for years is a bit daunting. I guess im just asking for general advice, and any would be appreciated.

Yes there are usually groups that form throughout the week for level 60 and 70 raids. I personally have run Molten Core, Blackwing Lair, and Temple of Ahn'Qiraj every week for about 2 months.

If you want my opinion, get to 80 then run all the old content you want. Certain groups don't like taking low levels along for the raids (myself included), and you'd be more of a burden if anything for people trying to get the raids done fast/smooth.