I’m looking to educate myself as a stepparent, help

My partner’s kid is NB- trans masc. I want to educate myself on the community but have no idea where to start, what is reliable/helpful info, and truthfully some of the things I’ve read just confuse me more. I’ve asked them before to explain it to me and I’ve gotten back “it’s not my job to educate you”. I took a course in university regarding gender so I understand that sex and gender are not the same thing. I’m really just asking for some help, I already support them no matter what but I do want to understand and be educated.

Specifically, I’d like to understand the differences between gender identity and gender representation.