general dating advice

Can someone give first time relationship/possible dating advice? Like, how long do first relationships realistically last, what to expect/what to..idk, do?, how to tell if a guy's flirting, that kinda thing. Like, if he were to ask me out and I was interested what would that mean (high school age wise), asking me on a date or asking me to be his girlfriend? I feel so dumb asking this but it's one of the "at this point I don't know and I'm kinda scared to ask" things😂