Should be on the home page, perhaps even above the fold already asking you a question with a side-by-side of the flowchart components being activated/highlighted.
That's a super good UI suggestion, thanks. We just launched our public beta about 6 hours ago and have been thrilled with the response and very unique bots being created (particularly when people leverage IFTTT and Zapier too) ... we'll definitely be surfacing as many cool uses as possible ASAP :)
A sandbox server that allows developers to connect through pidgin would be a great way test their bots in real-time.