Link creates a "notification"

What I want to do is once a player collects a note, a little box pops up on the bottom right saying “Note Was Added To Key Items!”. All I have for now is just some text like this:

You decide to take the note, putting it in your pocket. <br>(Note has been added to Key Items!)

I would prefer if it was a box on the bottom right that said “Note has been added to Key Items!”.

There are a couple of third-party SugarCube macro addons / libraries that can be used to display a “notification”. One of them is Chapel’s Notify Macro, which is part of their Custom Macro Collection

note: you may need to change the addon’s default CSS so the panel appears where you prefer it to.