From the Catalog, click New and select Track from the menu.

If you want to edit an existing track, navigate to it, open the context menu (button with three dots), and click Edit.

The New Track page opens to Details & Settings.

Enter a track Title and Description and add other details about the track.
See the Go deeper section for more about the details you can configure.

Open Track Items at the top of the page.

Click Add Content.
The Add Content to Track dialog opens.

Use the Content Type filter and search for the Name of an existing content item you want to add.
OR
Click Create to add a new content item to the track.
You can create an Event Type, Article, Video, Course, Codelab, or Task from this menu.

Select the content you want to add and click Add to track.

Optionally, reorder the added content by dragging-and-dropping it on the left side of the Track Items page.

Optionally, use the Add section option to organize track items in sections.
For example, for a scheduled track you might have a section for Week 1, another section for Week 2, and so on.
For more, see How to organize a track into sections.

Click Publish (or Save if you're editing an existing track) in the upper-right.