Where is my Appearance —> Editor?

Hello,

I am a newbie here and created my first WordPress site a few days ago. I use a Chromebook, and therefore don’t have the ability to install WordPress (as far as I know) on my computer. I have been using the WordPress web application.

My problem is that I have no idea how to access my WordPress php files. “Editor” is not an option under “Appearance”. In other words Admin –> Appearance –> Editor doesn’t exist.

Is there another way to access my files?

Thank you.