Michael Dean and Chris Caulder have released a CC-licensed (and free) eBook about making music digitally: Digital Music – DIY Now!
The book claims to be “for people who want to record their own compositions and get them out to the World” and “for people who want a career making music for films, TV, and video games.” It’s definitely more the former than the latter: Long on technical details (aimed squarely at beginners,) and short on anything I’d call “career” advice.
That said, the book is worth checking out for the thoughtful introduction to songwriting, and the closing commentaries. (Chapters 1 and 12.) One of my favorite quotes: “You can’t become a better or more creative musician if you listen to only one thing, all the time, and write it…“