There are very few legal sites, and those do not openly invite new members to join. They all have long waiting lists and nobody ever leaves once they get in.
The legitimate sites pay very little, maybe $0.25 per survey, and typically one gets 3 surveys a month. Some sites pay only in points, and it takes many months to accumulate enough to get small things like a set of headphones.
Further, since you're only 16, you are likely a student and have little or no disposable income. Most surveys want responders who are consumers, homeowners, etc - who have the potential to buy & use their products. You will likely be rejected from most surveys.
So do not get your hopes up. Any survey site that promises lots of money is very likely to be a scam or ID theft threat.
I have been a member of survey sites for years. My typical earning is about $3 a month, there are many months where I earn less than a dollar. In all my years of surveys, the most I ever made in a month was $10 - and only once.