I was just as new to this as you, which means I wasn’t even sure how to read half the stuff related to modifying PATH. Eventually though I came upon a way to do it that doesn’t require you to put subl into the .rvm/bin (since that is for something else) but in its appropriate directory, which is ~/bin.
Go to your terminal and type:
open -a Finder /usr/bin
This will open your Finder to the /usr/bin directory. Once you’re there open a new Finder, go to Applications, right click on the Sublime Text icon and go to Show Package Contents, then to Contents, SharedSupport, bin. Copy the subl file and paste it into the other Finder showing /usr/bin
That’s it! You should be set to use the command:
subl . (or subl file.name)