Rails 4 install

I’m newbie and installed Rails last week. When I did rails -v in cmd
prompt, I got this:

C:\Users\oliver\lesson3>ruby -v
ruby 2.0.0p0 (2013-02-24) [i386-mingw32]

C:\Users\oliver\lesson3>rails -v
‘rails’ is not recognized as an internal or external command,
operable program or batch file.

I want to upgrade or install Rails 4. Does this mean I don’t have Rails
installed? I used RailInstaller 3.0 last week to install Ruby on Rails.

It doesn’t look like rails is installed.

No idea how to do it on Windows but on Linux or Mac I would suggest
running, gem install rails

ok thanks.