But I am on Windows and I don't now how to use the Makefile created by extconf.rb

I tried Unxutils and Cygwin, but it didn't worked (maybe I don't really know how to use them).
How can I get a chipmunk.so file from the source code of the last version?
(I have found on the web a chipmunk.so file, so I can use Chipmunk basics functions, but it is an older version.)
Thanks a lot!