How do you decide the bins initially in Real AdaBoost?

I understood AdaBoost pretty well. I am trying to implement Real AdaBoost for a class project.

I am not getting the idea.

Here's the paper I referred to-

http://media.cs.tsinghua.edu.cn/~imagevision/papers/FG04-113-WU_B.pdf

What I don't understand is how to decide the bins initially.

Thanks a lot!