How does weightlifting work?

I am 16 years old and I want to start weightlifting but I don't know what to do. I have a gym near my house but I don't know what machines to use to work specific body groups. Also, considering strength training can be dangerous for growing teens, I don't know what types of exercises are bad for me.





If one day I work upper body, can I work the lower body the next day? Do I have to take a day of rest even though I am working different muscles?





Need help, please enlighten me all you experts out there!?|||I'm no expert, just do it a couple of times a week, however I was in your position a short while ago.





Essentially, start with a weight level you can do 10 repetitions with. This is one set. Do 2-3 sets of each exercise with about 30s break in between





When you can do this easily, or after say, 6 workouts of that muscle (spread over about two weeks) increase your reps by 1-3 depending on how hard you want to push yourself.





Don't go above 3 sets of 20 reps if you are building size, anything more is just building stamina.





For specific exercises, just Google "how to exercise _____"


(good idea to learn what the muscles are called, makes it much easier)





If you are just starting, it could be a good idea to train with just your bodyweight. (called calisthenics training, push-ups, sit-ups, pull-ups,etc)





I prefer to work out my whole body in one day then cardio (running, etc) the next, then weights, however that is up to you. It is recommended that you only work out a muscle every other day to give it time to rest.





Good reading here, definitely have a look: