That's the whole point - they know they want "Lisp" because of something they heard someone say, or because of something they read. That's all they know. Expecting someone to understand the Lisp ecosystem before getting started is unreasonable.

Lispbox would be a great way to get started, and you don't need to know anything about the different varieties of Lisp until you start trying to make something you'll redistribute (which isn't what newbies are doing at first anyway).