You want to be a manager and do not know how?
When I was young like you, I wanted so much to be a manager of my department (the place I worked). But sometimes I wonder to myself, how will I do it? Even when I became one, I did not really do as well. Later on I became an Internal Auditor and that is when I realized it was easy to manage anything. You can even become a CEO and manage a whole company easily.
The key is realizing that every organization has an inherent purpose for being there. Let us start at being a CEO of a company. The company was created to make money for the stockholders so that will be your main objective or job - to make money. Of course, you will learn that there are limitations to what you can do. You must make money but must follow the laws of the land; and to consistently make money over time, you will need to hire good people, make them happy to retain them, etc. But the job is still to make money.
Let us say you become a manager of the Accounts Payable Department. Logically your objective is to pay your vendors on time and effective - or correctly, in accordance to company policies. You have to be good to employees, attract the right people and retain them.
This should start you now. It is really simple. Just do it and good luck.