How do you create a drip campaign?

Hi. I'm sure this must be in the forum somewhere, but I haven't been able to find it, even though I've seen lots of people talking about using drip campaigns. How do you actually create one? I'm on the version 1.1.8.2, and all I can see is to schedule a campaign on a date, not to schedule it to send x days after the last one, or after a subscriber joins.

Thanks very much! John.