I (22M) have an online friend I’ve been talking to, “Ana”. (20F). Ana asked me out. I don’t know how to be a good boyfriend or what to say. I’m an anxious mess who’s been largely unnoticed by girls even in high school. Because of this, I said “Sorry, no,” even when I did want to be asked out. I cried about it because I felt bad but also because someone actually seemed to want me.

Just because they asked you out doesn’t make you their boyfriend, that comes later.
For dating? Just go out and have a good time. Relax, enjoy yourself. You’ll be better for it.
The boyfriend thing will come later.