After signing up, you'll be asked to setup an instance, or WordPress install. This shows up as the following form:
The instance name refers to the name we call it internally. Also, it's the username you'll use to connect via SFTP or git push if you need to.
The Domain Name will be mapped to your instance on creation. Note, if you've not already pointed DNS at our loadbalancer IPs, the instance will not be available till you have!
The Site Title is your new WordPress site title. We setup the WordPress install for you automatically, and it's the only thing we need to know to complete the install