There are two steps to creating a node to be displayed as an expandable outline. First, you have to create the outline, then you have to link to it from an outline node.

A simple way to start is to create a new file with File/New, possibly in a Dropbox public folder so it has a URL and will automatically synch. Then fill in some stuff for the outline displayer to display. Save it. Get the URL onto the clipboard, ready to be pasted. For my demo I created an outline of a the Major League Baseball teams, organized by division.

Now, open your world outline (choose Open My Outline from the World Outline sub-menu of the Outliner menu), and create a node to link to this outline. Where you put it doesn't matter because you can move it.

Right-click on the node, choose Add Inclusion. Paste the URL and click OK. Verify that you have the URL correct by expanding it. The main heads from the outline should appear as subheads of the node you expanded.

Now, a little hack. With the cursor on the include node, choose Set Nodetype from the World Outline sub-menu of the Outliner menu. Enter outline and click OK. Save the outline. After a few seconds, click View. If it worked you will see something like this.

Click the wedges to expand and collapse.

Now you can go back and edit the included outline, to change the outline on the website. You have to Save to make the changes visible (assuming you used Dropbox to host it so it can be updated automatically).

For background and more links see this Scripting News post.