Ruby on Rails

hi-Im use cygwin and want to install rails (gem install rails)
I have error please help me


$ gem install rails --version 4.2.1
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.

/usr/bin/ruby.exe -r ./siteconf20150407-7680-1fo1fpe.rb extconf.rb
checking if the C compiler accepts ... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details.
You may
need configuration options.

Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/bin/ruby
--help
--clean
/usr/share/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to
generate a
n executable file. (RuntimeError)
You have to install development tools first.
from /usr/share/ruby/2.0.0/mkmf.rb:549:in `block in try_compile'
from /usr/share/ruby/2.0.0/mkmf.rb:500:in `with_werror'
from /usr/share/ruby/2.0.0/mkmf.rb:549:in `try_compile'
from extconf.rb:80:in `nokogiri_try_compile'
from extconf.rb:87:in `block in add_cflags'
from /usr/share/ruby/2.0.0/mkmf.rb:599:in `with_cflags'
from extconf.rb:86:in `add_cflags'
from extconf.rb:337:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in
/home/mohammad/.gem/ruby/gems/nokogiri-1.6.6.
2 for inspection.
Results logged to
/home/mohammad/.gem/ruby/extensions/x86_64-cygwin/nokogiri-1.6
.6.2/gem_make.out

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