After read the post in Ruby-China say how to use mechanize and curl to login Ruby-China, I decide to install curb, seems still a little tricky.
Notice most up-to-date version
curl-7.47.1-win32-mingw not working, so still using 7.40.0.
Extract to C:\ and install the curb via below command.
Finally, need copy all DLL and EXE file in