Sure. And thank you.
I upload using the "Insert/Edit image or media" icon in the edit page screen seen here:
The files upload just fine as you can see by the pdf in the list in the screenshot below. However, I'm unable to select it to then insert it into the page. The image that is also in the list is selectable and can be inserted. So it appears this only happens with non-image files.
Once uploaded, it shows as an attachment to the page, but there is still no option to insert it into the content of the page.
Let me know if you need any more information. I'm very new to Kentico, so it's possible I'm totally missing something simple.
Best,
Jaime