Now that the RVM scripts are installed, you need to load them every time your start a new Bash session. This is achieved by adding a line to the end of your ~/.bash_profile file. You can add this line with your favorite text editor, or by using the cat command. Just hit Ctrl-D after you've typed the line and it will write that line to the file and return you to the bash prompt.
$ cat >>~/.bash_profile
[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"
After that, close the terminal window and open a new one.