Rails (aka ruby on rails), is a collection of ruby related products.
On windows, it is possible to install Ruby, and install rails separately, however it is much more trouble-free if you install them together using the railsinstaller.
You might also need to add the following variables to the path variable:
Note, the ruby version numbwers could be slightly different, so first locate your bin directory and ensures that it exists before adding it tot the path variable.
This bin, directory above has a number of essential ruby/rails command line utilities.
Now open up a powershell terminal and check what version of the tools we have installed:
PS C:\Temp\rails> ruby -v ruby 2.1.5p273 (2014-11-13 revision 48405) [i386-mingw32] PS C:\Temp\rails>