It's a very good book. Shows a lot of different tunings that make playing a dulcimer more interesting. Playing by ear and singing with it is the way to go. You can learn to read music later if that's what you want to do. I personally don't like tabulature it seems a dead-end method that doesn't lead anywhere.
I can't remember if this book has them but there are different ways to hold a dulcimer. I found holding it upright against my left shoulder like an auto harp is an interesting possibility. You can strum in a way that is more like using a guitar. The book I saw it in called it "The Volkswagon Stlye". Of course you can hold it like a guitar too. Have fun and good luck. Joy