Oh right, OT.
If you want to start with FTB, more power to you. Just know that it's a lot bigger and much more complex because it's a mod pack with plenty of mods to choose from.
I do suggest getting a good grasp on what is vanilla, but that does not mean play vanilla. The Official Minecraft Wiki will help with that(and might help with other issues as a side note) and the FTB Wiki would likewise help with FTB stuff.
I warn you, though, I get somewhat miffed when people post stupid questions that could be answered by a FAQ thread or wiki, and I'm hardly the freak here in that regard.(IE don't ask questions that show you know nothing)
It's worth noting though that if you're new to Minecraft, let alone FTB, you might have some problems finding a server that accepts you. I've been on servers where you don't get permission to do anything save for walk around and get killed until you prove you aren't a "Squid". And while I have no idea if that's the norm, just keep in mind you'll want to get a grip on the basics of mods in FTB before playing on a server. Not a thing you have to do, but it helps avoid the stupid questions issue.