Soon as you log in, and have subscribed to a plan, you will be able to make a new app.
Next, you should enter the app name and app id in the fields like in the picture below.
After that choose a template, for now, you can choose between 12 templates, but stay tuned, new templates are coming soon. Templates have already created an app with the basic sections (ex: Conference template contains: agenda, the location where the conference is, buy a tickets section, social and etc). You can add or delete a section, it's up to your needs.
In the end, you have to choose a layout. For now, there are two layouts (tabs and side). But very soon grid layout will be included.