make a proxy with two servers

I want to implement a proxy which has two (A and B) servers in the middle. traffic goes from my computer to server B and then to server A and then gets the data.
I found that with this configuration in ~/.ssh/config:

HOST B
    HostName B
    user debian
    DynamicForward 0.0.0.0:1081

I can use my 1081 port as a proxy. But now I don’t know how to proxy all B’s traffic through A.