After logging in to the site through the credentials you are provided with, you shall be redirected to the sub domain page.
Here you may choose the Domain, Sub-domain, how you wish to host your site, and if you want to change the design then you can do it easily from here also.
As per your selection you can create the site with us.
As and when you saved the changes in your picked design, the system will create site for you according your selections. An email will be sent to you, that your site has been created.