Edit some text in a music tutorial book

I have finished a music tutorial, which has a lot of technical information. Interspersed are some illustrations, which contain text. I'd like this to be checked, as well as the introduction and 'about me' sections. In total there's about 30 small paragraphs, most of which will not need any changes. The most awkward paragraphs are the introduction, which I've provided a copy of.