Celestial Navigation by H.O. 249
Here is a basic, beginner's book, introducing the newcomer to the tools, the vocabulary, and the techniques of celestial navigation.
Among the recommended tools are the H.O. 249 tables, the most widely used among amateur navigators at sea, because of their simplicity.
If you can read, add and subtract, you can learn to navigate in your armchair, or at sea, from Celestial Navigation by H.O. 249.