How do I Add Text In The Source Code?

In which theme?

The theme I use is Ink, but I can use any I suppose.

Not sure I understand what you need. Could you expand upon what you want to be happening.

Just comment out the text you want to hide.

HTML comments:

https://www.w3schools.com/tags/tag_comment.asp

PHP comments:

https://php.net/manual/en/language.basic-syntax.comments.php

RossMitchell, I would like to put relevant text in the source code that Google crawlers can read but the real visitors can’t see.

Dave Naylor, where would I put the <!–…–> code? I’m in Appearance-Editor-(mytheme). Or do I put it in the actual page editor in the Text tab?

Well, you said:

I want to add text in the source code

so to do that, in a text editor, open up the theme template that you want to comment, and enter your text.