... or maybe three.
Many years ago Time-Life published and outstanding book on Basic Electricity for Homeowners. I still see this book from time to time in used book stores in the Home Repair Section. They also pop-up on Ebay I just gave mine to Goodwill. Sorry.
You'll need a book like this to understand basic electricity and the 120 volt, DC system in your Airstream.
There are any number of basic automotive-electricity books out there to guide you to an understanding of your Airstream's 12 Volt
DC system. You can't learn about solar until you understand 12 volt
Once you understand 120 volt AC and 12 volt
DC thoroughly, ask us about converters, inverters, and solar charge controllers.