upgrade ruby on rails on mac sierra error

I'm having problems to update my ruby and install rails, everything seems to be installed

brew install rbenv ruby-build
Warning: rbenv-1.1.0 already installed
Warning: ruby-build-20170405 already installed
thiagos-Air:~ thiagobaptistella$ rbenv install 2.4.1
rbenv: /Users/thiagobaptistella/.rbenv/versions/2.4.1 already exists
continue with installation? (y/N) n
thiagos-Air:~ thiagobaptistella$ ruby -v
ruby 2.0.0p648 (2015-12-16 revision 53162) [universal.x86_64-darwin16]

system MacOS Sierra version 10.12.4 (16E195)

For that reason can't instal rails.

any thoughts ?

thank you