Hi @Dave104, glad to help you with your question. I’m sure, my given answer will help to solve your problem by following given steps
Go to Online Store > Customize > header > announcement Bar Text
And paste this code by replacing “yourlink.com” with your desired link
<a href="https://yourlink.com" target="_blank">Announcement bar link</a>
Hopefully, that solves your problem. If not, please let me know if you're seeing any other issues.