How do I add the Applications folder to the terminal PATH?
You can easily add the Applications directory to your PATH but it will not do anything useful as it is a collection of OSX apps which are bundles and can't be run from the command line.

There are several alternatives


Use the open command which will open any OSX app e.g. open -a Sublime\ Text.app source.php This works for all apps
Find the unix executable in the app bundle usually in Contents/MacOS and with a similar name to the app. 
Some apps e.g. Sublime provide a specific command line tool and use that. This is what is suggested in Sublime's documentation However I would just create an alias to the full path "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" and use the full path in the EDITOR environment variable