XF 2.2 Theme migration


I transferred webhosts a few months ago and decided to upgrade my xenforo forum software entirely, since I didn't have many users.
At that time, I exported my website and database and saved it to my machine. Following that, I installed xenforo from a clean installation [which meant that I didn't get to upload my custom theme].

My main question is: How do I import a theme based on the files only in the folder?

Would I have to upload the old forum and export the style, then import it? Or is there a way to import a theme from some file in /styles/ [eg]?