Hey, there, I think it's great you want to help your brother out! Have you tried talking to him, or has he come to you about this yet? I think it's best to sit down with him and come up with a plan. Educate yourselves on how to begin a business, what you will need, how to make it successful. Does he know what he want his business to be?
After you both have prepared and educated yourselves, then you should talk to your father. It is your brother's decision what he wants to do with his life, not your father's decision. Best of luck!