how to concrete on studies ?

Don't believe them when they say that your brain is weak. Don't let it pressure you. Don't push yourself. Don't try to please people. What you really need is to enjoy what you are doing. Learning is a process. Give yourself a chance to listen, speak and live the things you are learning. We all start from knowing nothing. Even your teachers didn't know anything when they started. The first thing you need to do is to learn not to see yourself different from everybody else. You are a magnificent being, trust in yourself that you can. Find help, allow people to help you also. You are not alone, there will be people around you who are willing to help out, you just have to trust and allow them to do that. Don't feel bad, don't let anybody make you feel bad. Accept the fact that people know nothing at first... then let the things come to you, keep them, learn from them, and then be happy. Appreciate yourself. There are things that you can do that other people don't. Be thankful for that. You will learn, you can learn. Help yourself, and let others help you too. It will not all happen over night, it will take time, just be patient. Keep smiling.