I have a possibly great idea for you! Since you are in high school, you still have access to clubs! My experience with weightlifting clubs at high schools (yes, plural) at least in my area is that they are run by instructors who really care about students' health and self-esteem. You will learn safe and effective movements and methods. My experience with weight-lifting in gyms (yes, plural) even with athletic looking guys is that you will be respected for trying, even if you are a fat girl like I was. This should also be free of charge, and you mentioned you don't have much money. Joining a gym or even buying a few free weights costs money, but the high school weightlifting club should not. It's worth checking out to see if you have access to such a service.

Weightlifting has been of tremendous value to my health, mood (endorphin kick for hours after lifting session), and ability to do things other women cannot. And, once again, I am not an athlete or terribly concerned about my appearance. However, it's well known that building up some muscle does make you look better.