Just a follow on to what Intruder has suggested: I recommend Global Navigation For Pilots (ISBN-13: 978-1560273127) by Dale De Remer as a good start to your study of navigation concepts. I read the first edition of this book long ago and it really helped me form a solid basis for future learning. And it contributed to piquing my interest in the subjects of maps and navigation to such a degree that I'm still interested in learning more!
Just do a quick search and you'll find this book online. There are several other books available on related subject areas as well...