to learn x3d, I need to practice it and write it, the best way for me is to make it an interactive tutorial,
you read the lesson (easy), and in the box on the right side you write the code for the lesson exercise, are you interested?
the thing being quite long, I will only do it if you are really motivated
If you prepare a nice X3D tutorial, I will certainly be interested in watching it. You can e.g. post about it on this forum, in this thread.
If you’re interested in linking to it somewhere, you can contact e.g. https://www.web3d.org/x3d/content/examples/X3dResources.html maintainer (see the bottom of that page for contact info), that page collects a lot of useful X3D links. You can also post about it to public x3d-public mailing list ( https://www.web3d.org/mailman/listinfo/x3d-public_web3d.org ).
If you do it, people will use it. I will but I can’t promise to be motivated:)