Good morning Jordan and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
Normally, the easiest way to accomplish this would be via the Advanced Template Settings found in Events -> Settings -> Display.
However, since your needs are pretty specific (only future events in a specific category), you will have to accomplish this via a template customization.
You might want to read our Themer’s guide to get a sense of how that works.
Basically, you will have to modify the single-event view to add the text when your required conditions are met.
Let me know if that helps.
Have a great day!
Geoff B.