I know in my geographic area we have no Natural Family Planning (NFP) teachers. I'm sure there are many other people in the same situation. Or, perhaps you simply can't get out of the house to take an in-person NFP class. In any event, I was very excited to find out that the Couple to Couple League offers on-line classes. You can find out more at Home Study Course
While I was perusing their site, I also saw that they offer books dealing with NFP when it is difficult to chart (i.e. during breastfeeding and premenopause). Visit their Manuals page for more information.