I'm very new at deployment and I have been mostly working on windows machine. So what I'm trying to do right now is to update the droplet version from using ruby 2.1.3 and rails 4.0.2 to using ruby 2.0.0 and rails 4.1.4.

I have been trying to look up tutorial on this but so far I found nothing, any suggestion would help thanks.

Droplet is currently in its default set up
Ubuntu Ruby on Rails on 14.04 (Nginx + Unicorn)
Ruby 2.1.3
Rails 4.0.2

Update:
Successfully changed to ruby-2.0.0-p481 with rvm
rvm use ruby-2.0.0-p481
or to set it to default
rvm --default use ruby-2.0.0-p481

still working on rails