This is a decent introduction, but I'll summarize the basics.
First, you want to avoid shampoo and conditioner with sulphates and silicone. These chemically relax your hair and build up over time. They work great for people with straight hair (i.e. the majority of the white population that beauty companies target), but not for people with curly or wavy hair. My products of choice for this are Shea Moisture Coconut and Hibiscus Curl and Shine Shampoo, as well as the Conditioner of the same range.
Once you have these, you want to cleanse your hair of any built up silicone. This will take quite a while (took a few months for me), because the other main thing to remember is that you should only really be washing your hair once a week. Most people with curly/wavy hair just don't need to wash it as often as straight haired people. You should also only be brushing your hair while it is wet in the shower.
Then there is technique, which I've found isn't as important but does help. When you dry your hair, you're supposed to do a thing called "plopping". You put a towel on a flat surface, plop your hair onto it, and then tie it up into a headwrap thing.
Finally, the rest of curly girl is just experience. You will get to know your hair and how much conditioner and care it needs. It takes a while but is very rewarding!
At some point in high school, before I was even considering that I might be trans, I just thought about how it was a cute name. It stuck in my head for a reason I couldn't figure out for like 4 years after that, until the reason slapped itself in my face and I started transitioning.