There's no stupid questions ;)
Installing phpMyAdmin on GAE Standard has the advantage that it is always available but only costs you when it is used (and is probably within the free tier anyway). Installing phpMyAdmin on GCE will charge you for the GCE instance as long as it is there, but is closer to traditional phpMyAdmin installation so might be easier.
Installing phpMyAdmin on your local machine is probably not the best solution, as it means you would have to run a webserver locally. If you want to use a GUI locally, you're probably better of with something like
MySQL Workbench or
HeidiSQL.
If you want to proceed following the guide for phpMyAdmin on GAE we can help. What about the blowfish step has you confused?