I have purchased some of The "Professor Teaches" computer programs for my daughter. I believe they have Excel too. She is 11 and did not have any trouble with using it.
It is a CD,though I think It is also in textbook form.
I use Excel everyday - I work in accounting. There have been times I would want to do a certain function and would Google it and would find a Youtube video.
Here's a link to Excel basics. Learn Basic Excel Skills For Beginners || Part 1
You may also try your local library to see if they have CD's and books that you can check out.