Can someone please explain FIFA 12 Youth Academy in full detail please?

Searching for new talents is long and sometimes difficult job, but if done properly, you can find and develop some pretty good players. Of course, it depends on what you are looking for, 90 overall players don't grow on trees.

First, you must hire a good scout, based on their experience and judgement and you financial capabilities. Always look for the best scout available, they change from time to time, you don't have to hire one immediately.

Once you hire scout, send him to one of the countries to search for talents. I haven't noticed some general rule which countries or regions of the world are the best, but i prefer some African and eastern-European counties. You have few options on duration of scouting, 3, 6 and 9 months. After that period expire, you will have to set up scouting network all over, but you keep the scout.

The more time you spend scouting, the more players you will find and for each you will get more details. If you keep scouting for a long time, more precise scout's prediction will be. Results of scouting are based scout's experience and judgement and, obviously, luck. When you first find a player, his predicted overall can be something like 44-75 and longer you scout him his predicated overall will narrow down to like 68-72 overall (this is only an example). It's always good to keep scouting player for some time, but the problem is you can never know when he'll be lured by another club. So try to keep scouting for longer periods of time to get know the players better, but be aware there is a risk.

If you decide to sign the player and send him to your youth academy, he will have more observation time. His ratings still won't be precise, but you can get to know him even better. When he turns 16, he will be eligible to play in your first team and you can offer him a contract. If he accept you will be able to put him into your squad and you will get precise value of all his stats. He will develop over time, the more games you give him to play the faster he will develop (in theory).