For the life of me, I can't figure out how to add a tag to a contact

I’m new-ish to Keap. Was tasked as a contractor to design/send email campaigns. Now I’m an employee for the same company and it’d be helpful to add some tags to contacts. How do I do this?

https://help.infusionsoft.com/help/what-are-tags

https://help.infusionsoft.com/help/search-and-tag-contacts