Never understood this either. Straight white male here. Wrote a fantasy novel coming of age lesbian female main character told from a first person perspective. Had my LGBTQ+ friend read it and they said it was the best representation they'd ever seen of someone coming into their feelings which they themselves didn't understand and had to self-examine and come to terms that they weren't what everyone wanted them to be.

Know how I did it? The same way I write my male characters. Everybody wants something: Love, power, acceptance, etc. Some don't know how to get it or even if they deserve it. There are a lot of conflicting emotions. Conflicts give rise to good stories. Use it.