Advanced font management is only available in Pro subscriptions.
In the settings section, click Fonts in the column on the right hand side to access the list of all available fonts. You can enable or disable each individual font, which makes it available / unavailable for selection in the designer. This is a nice way of limiting the font choices for your editors.
From the main font page, you can start to add your own fonts. It's a two step process:
You can upload the file either by clicking the Upload TTF or WOFF file button or by dragging and dropping the file onto the grey area.
The bold, italic and bold and italic font files are not strictly necessary. If they are not present, the web browser will do its best to render a bold, italic and a combined variant. But for the best quality, uploading style-specific font files is recommended.
You can upload TTF and WOFF font files. We recommend testing the fonts on your playback devices to make sure that they are displayed correctly, since some older browsers don't fully support TTF or WOFF files.
The list of system fonts simply allows you to enable or disable the font availability in the designer. Be sure to click the Save button all the way down on the page when you have made any changes.