Cant find HTML Editor on WordPress

Hello,

I recently purchased the Premium package hoping that I could get a template and edit the HTML myself to make a few tweaks. I cant seem to find where the EDITOR button is to access the code. Can you not edit the html of the template other than specific pages?

I see where I can edit the css, but I want to view the whole code of the entire template. Sites I have edited before had an editor button under the appearance category.

Please Help!