The best thing you can do for this kid is improving yourself. As much as you possibly can.
You may never even need to show him this site. Humanity has existed long before SoSuave. Guys were still getting laid. There was still players. There was still a select few men who just "got it", and understood the importance of improving themselves and reaping the amazing effects it can bring. Woman being one of them.
The best thing you can do for this kid is to personally SHOW him and lead him by example. If you have always been that big brother who showed confidence, seemed fearless, was always good with the ladies, hard working, smart, charismatic, social, and overall just a good person to look up to then he WILL come to you for help. At the same time, he will also LEARN by example.
A lot of us have learned a thing or too just by silently observing some of the guys that "just got it". Or at least I know I have. We are surrounded by it constantly. Do you ever remember a point in your life thinking "How does that jerk always get the girl?!". This would be one of those moments. Even if it didn't make sense at first, when we came to this site it was reconfirmed with us and we learned WHY it works. We don't always need to know WHY something works at first, but just know that it DOES work. With time we will learn. I remember practicing C+F before this site. Just from silently observing the guys who were getting girls and how they were acting etc..
Take this same philosophy with your brother in mind. If you are seen with many beautiful woman, you will get the reputation as a "ladies man". Your brother is going to follow in your footsteps because you are older and he looks up to you. So be very careful because kids can be very impressionable. Lead him by example. If he ever stumbles or has a question he will come to you. Or just simply give him a slight nudge in the right direction.
Ultimately though... helping yourself, will help your brother.
Remember that and take it to heart for the rest of your life.
-Scars