I am trying to update the Header php file so I can insert Adsense (I am using the Nirvana theme). I am expecting to see an ‘Editor’ option under the Appearance menu, but there isn’t one – there is only an ‘Edit CSS’ option and that takes me to an option where I have no idea what to do. Could somebody please tell me how to find the ‘Editor’ menu so I can access my theme files?
The editor functionality is built into WordPress and not something under the theme’s control. You may be using a user that doesn’t have enough permissions to use this or something (a plugin or setting?) is blocking it.
Either way, you should use a plugin to add the adsense code and not mess with the files. It’s safer and update-proof.