Youth Academy is the fifth screen in the players menu. The academy is the best and quickest way to develop your own players. The academy screen has a variety of options. You have an initial investment which will affect the age.
Ten thousand dollars will give you a seventeen year old player and then it scales to one million dollars giving you a thirteen year old player.
Each player will start with three in every stat except personality, that will be zero and a starting wage of $310. They must be trained each day in order to improve, the amount of daily investment will determine how much the growth. You select one stat to focus on, that stat will grow at twice the rate of other stats, every other stat will grow at the same rate except for personality which will not grow. You are allowed to hire the academy player at any point, as long as you have an open slot in your starter team. Academy players will not take up a slot on your team until they are hired. They also can not be trained by coaches. You are allowed to name the player anything you want before hiring them.