I do not know what it is called but when information is highlighted green and you can hover your cursor over it and the information pops up without clicking on it is what I am curious about. Can you make a notes section in My Campaigns with these types of pop-ups? I know how to make hyperlinks but I would love to know how to create the popo-ups so I do not actually have to leave the main page of My Campaigns. Thanks!

[xspell]spell name[/xspell]

But take out the X's

ray of frost becomes ray of frost by removing the spaces between the brackets and the spell name (before ray and after frost), for instance.

Edit: Ignore that, I'm dumb lol. I didn't realize the spaces didn't matter.

1. Put [spell] before the spell name.

2. Put [/spell] after the spell name.

They're called tooltips. The thread you want is:
https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/9811-how-to-add-tooltips

Thank you