One of the best ways on what to do when your nine year old brother is annoying is to ignore him. If he gets really annoying, you can tell him that you love him and walk away. This will also show him that you are old enough to treat him with maturity as well as respect. Read more on http://www.wikihow.com/Get-Your-Little-Brother-to-Stop-Bugging-You.
Just ignore him. It's part of a younger sibling's "job description" to be annoying. If you ignore him, he'll get bored with trying to bug you and find something else to do. When you're both grown up, you'll find you really do appreciate and love each other. Until then, you're just going to have to deal with it. (Said as the oldest of 5.)
Hit him in the left eyeball. Jk don't do that, you will probably get in trouble. But if he's being annoying maybe he just wants attention. Maybe he feels neglected so he tries to get your attention by annoying you. Just be nice to him and play a game with him or something. Play tag or super heroes or put pillows on the floor and don't touch the 'lava'.