My ribbons have disappeared, and I can't get them back!

I was watching Primus live just before (great concert btw) while doing some homework and keeping an eye on my e-mail, and so to maximise desktop space, I closed the ribbons (or whatever they're called) at the top of the Firefox screen - you know what I mean, the thing with "File -Edit - View - etc.", and the other one with "back" button and some other stuff that I can't remember right now. The problem is, I can't figure out how on Earth I get them back again; can anyone please help me?