This is a misunderstanding.
You need to open the Outline view (or the repository) as explained in the previous step (Reuse a Data Structure to Define Table Contents), and drag it from there, as in the following screenshot:
Your screenshot indicates that the Repository/Outline views are hidden, because you've closed other views, and/or maximized the model editor, and/or you're not using the Modeling perspective.
I suggest you do the following:
I hope this helps you get back on track.
For best results, use the Firefox browser..