I'm new here so, you know, I don't know what I'm doing.
Is there an FAQ or will I just pick it up as I go along?
Look at the pictures, think of a funny caption, and write the caption underneath. If you've seen
Mystery Science Theater 3000, you can use that as a model; the jokes that Joel or Mike and the Bots would make are typically suitable.
Since you're new, you won't be able to get the pictures to show up for you, but that changes when you have enough posts (50? 100? I don't recall), and in the meanwhile, just reply with the pictures present for yourself and someone will almost certainly make a reply that quotes your captions and thus let other people see the pictures with your comic response.
On to my efforts:
``Jadzia! I've found the hole that leads to
Laugh-In! There's Jo Anne Worley! And that's Henry Gibson! Yoo-hoo, Ruth Buzzi, are you out there?''
Oh, no, on top of everything else now Harry Mudd's love potion has spilled all over the station!
``I don't know why I never before wondered how William Ware Theiss would dress me.''
``So, I figured nobody would notice the top deck was destroyed if we just set up a little duplicate bridge under half of our basketball court. I think Captain Sisko even likes sitting under the hoop.''
Little embarrasses Vulcans more than having someone walk in while they're mind-melding with themselves.