I have ruby 1.9.2p320 installed on my Mac and I tried to update it but don’t know how so I used rvm to install ruby 1.9.3 and once that had finished installing, after typing ruby -v I still get ruby 1.9.2p320.
Update
I now have ruby 1.9.3 installed thanks to Simone Carletti!
To install a Ruby version with RVM
then to switch to it
The latter command is probably the one you forgot to execute.
You might want to configure an .rvmrc file for your project in order to remember the settings.
About the other issue, you should open a separate question.