How do I even do that? I have the Facebook Connect thing-y on my sidebar... but shouldn't I get an achievement?

You get an achievement when Subeta posts something to your Facebook wall. You'll need to make sure that Subeta has the correct permissions to do so on Facebook as well.

Ah, okay. I actually just found a similar question half-way down the board, with the link to turn it on. This can be closed now!