Noob question about shifting and rpm

I’ve never even sat on a motorcycle before, but currently I’m trying to scrape together some money (18 yo) to buy some gear, take the msf course, and eventually buy a bike.Been “studying” yt videos so ik the basics. But when approaching stop signs and stop lights is it best to put the bike in 1st or neutral? Also in my understanding you have to be in a certain rpm range to downshift and or upshift without having the bike jerk. How do you raise or lower the rpm to be able downshift and upshift? Stupid question ik 💀 but any help is appreciated via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/e85ud8/noob_question_about_shifting_and_rpm/?utm_source=ifttt