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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