To set up Monthly Support, just go to your Monthly Support Dashboard.
You'll be taken through the steps of setting up Monthly Support; setting up a PayPal address (if you haven't already) and creating a Funding Goal.
At time of launch, only artists who accept PayPal are able to use Monthly Support. That said, if you don't have PayPal but really, really want to use Monthly Support, email us and let us know. We can try to make it work for you in the short-term, and if enough people request it, we'll definitely implement support for Dwolla.