I learned to navigate x-c mostly through books like this one.
The nice thing is you don’t really have to go outside to learn the basic skills. Of course, once you do it solidifies in your brain. Also, it takes time to really learn how to read a topo map and know how to choose your route based on what you “see” in the map. Learning how to cross country navigate has really become much easier thanks to phone GPS. Now you can train and then double check with your phone GPS to make sure you are lining things up the right way. I will the first to admit that I now mostly use GPS to navigate but I still pull out the Map and compass when I need to identify distant objects
To start off, I’d choose something easy. If you are willing to drive a bit to the Sierras from AZ there are plenty of “easy” x-c routes and passes that many others here can recommend such as Humphrey’s Basin, 20 lakes basin and etc.