Let's start from creating a new model. Login and go to the My projects page. Click the New project button. You can rename the project whenever you want. Then click on it to open the model editor.
The editor window consists of two parts. On the left pane you can see the model tree. We will refer to it as the model page. The right pane, called the details page, shows the details of the currently highlighted node on the model pane.
Initially, the model contains only a single root node. It has the same name as you called the model on the My projects page.