On the Mac you can activate the Quick Entry menu bar item in the Preferences. There you can also record a shortcut, which allows you to directly open QuickEntry at any time.
To start a new document, or take notes, click on the icon. Hit Enter to start a new line with a new item. This will be indented as a sub-node to the first icon. To remove the indentation hit Enter again. You can use Tab to indent further.
Use the tool bar items to indent, add tasks and notes.
When you close Quick Entry your notes are saved.
To create a document click the
Create Mind Map button at the bottom.
This will create a new document for you.