Google Code-in

Find some pages on Wikipedia that include musical scores. Create a Sandbox page for testing around as a subpage of your personal user page on mediawiki.org. Insert some musical scores there and play with the VisualEditor (not the classical wiki text editor) to understand how editing works.

Then create a separate section for editing musical scores in the VisualEditor user guide. This will be similar to the one for poems, but with different screenshots you will have to provide.