Hello Shirien Chappell, thank you for the follow-up. For your privacy, please cover your personal information before posting next time.
You're already on the right track—it's just a terminology difference. Your cell already has a “Comment”, and in your version that replaces the old “Note” option in the right‑click menu.
Please click Show/Hide Comments — you should see the red triangle appear in the top‑right corner of the cell, indicating there is a comment.
Hover on that and right-click > Format Comment > Colors and Lines tab > Fill section > Color dropdown > Fill Effects > Picture tab > Select Picture > choose your image > OK
Now the image should appear as background when hovering over the red triangle. Let me know how it goes!