Power Squadron also does a quckie GPS navigation course too. They may also offer the basic and advancd courses near you and are are some of the best there are and free or low cost. Take as many of the courses that they offer that you can. A lot of naviagtion courses are home study straight from the book but the PS courses have real navigators as instructors that meet over a period of weeks as you do workbook stuff at home. If you need a real instructor to help you this is the best way to go. My wife took the basic course and did very well.
Chapman Piloting is just a flat out a great book and covers about all you need to know on basic through slightly advanced navigation and a whole lot of other things. It's a big thick book with tons of drawings and pictures. If you could only buy one book I would pick this one.