To help me understand what you're looking for, could you tell me more about your brother?
For example:
* What was he like? Was he funny, serious, adventurous, thoughtful?
* What were his passions? Did he love sports, music, art, travel, or something else?
* What kind of life did he live? Was it full of adventure, challenges, or quiet moments?
* What are some memories of him that you cherish?
The more you tell me about your brother, the better I can imagine what his autobiography might be about.