Toni Weschler's book 'Taking Charge of Your Fertility' is the definitive guide to NFP, and she does include some info. about charting while breastfeeding. The regular NFP rules are modified in ways depending on how much/fully you're breastfeeding.
I would add, though, that there are situations where it is difficult if not impossible to use NFP. The transition period back to full fertility can last a long time and some women must consider themselves potentially fertile for much longer periods of time than others do. In my situation I had to consider myself fertile *all the time* for weeks and weeks on end (my son was 6-7 months old); so that method didn't work out for me.
In the first 6 months after childbirth you can use LAM instead of charting, which is very simple- as long as you breastfeed at least every 4 hours during the day and every 6 hours at night without supplements/pacifiers, AND your period hasn't yet returned, AND your child is less than 6 months old, there's only a 2% chance of pregnancy.