Billings and Creighton are slightly different, but I couldn't tell you how. I took an introductory class on Creighton. The charts are stickers, red for bleeding, green for infertile, yellow for basic infertility pattern (all the time mucus), white for potentially fertile. Count bleeding as potentially fertile. Count any mucus as potentially fertile (unless you have all the time mucus). Mark peak day as the last day of fertile mucus in a patch of mucus, and consider yourself potentially fertile for the next 4 days of drying up or dry. Count any days with known seminal residue as potentially fertile, and wait for a dry day to consider yourself infertile again. That's basically the simple version, but you could get a lot more information if you took a class. They encourage you to abstain for an entire cycle before you start so that you can observe your cycle with no confounding factors.
It's basically all you've got to do NFP before your first PP period, but it's hard to confirm ovulation. You can't really be sure you ovulated until you have a period. With the sympto-thermal method, you can confirm ovulation by charting temperature as well. If you dry up, and your temperature stays low, you know you haven't ovulated yet. If you dry up with a temperature rise, you know you ovulated. While bfing my DD, I did not chart until around 18 months when I had very fertile mucus for the first time since she was born. I took my temperature at the same time every morning as best I could. She still nurses 15-20 times most nights or just sleeps on the breast if I let her. There were times the temping didn't work out so well, but I was able to tell when I was potentially fertile (most of 3 months straight) based on the above rules. When I did actually ovulate, I had sore nipples when nursing, fertile mucus, and I had a clear temp shift coinciding with my dry-up. If I had been charting mucus only, I would not ave known for sure whether I actually ovulated or was just back into breastfeeding infertility until I actually had a period. By charting temp as well, I knew I had ovulated for sure. I knew I hadn't ovulated and gotten pregnant before without knowing. I knew my period might be starting or when I could take a pregnancy test. Those don't really matter so much as far as when I would consider myself to be fertile, but they gave me just a little more information to give me peace of mind and save me money on pregnancy tests.
The most research has been done on CM, and if you want to count on that one symptom alone, the Creighton folks know more about it than anyone. The Pope Paul VI Institute (Creigton) also came up with NaPro technology to naturally treat infertility. They have several physicians trained to look at your Creigton charts to determine what health problems you may be facing and to fix those health problems so that you can conceive naturally. They are highly successful, more successful than IVF for a fraction of the cost usually. I would guess that the book listed above is about NaPro technology more than the Creigton method, though they are connected. In any case, if temping isn't working out for you, Creighton is a great alternative that has also proven to be highly effective. Personally, I'd rather have whatever imperfect information I get from temping after nursing throughout the night, and I was surprised how clear my temping information was wen I actually got down to ovulating. I've had some temperature spikes without ovulating, but then the temp slowly goes back down instead of continuing up, and there's no dry up. Just wait an extra day if it looks confusing.... or post your chart for the chart stalkers to pick apart.