Creating an assets folder

I'm trying to create a data folder under the Media tab to store some xml files.  I'm able to create my xml files on the root of the assets folder without any issues.

I've found example code that just says 2 lines, not really helpful.

https://world.episerver.com/documentation/developer-guides/CMS/Content/assets-and-media/Content-assets-and-folders/

How do I create a folder called XMLFiles?  

I assume once it's created I'd use this to get the assets root:

_contentRepository.GetDefault<GenericMedia>(SiteDefinition.Current.SiteAssetsRoot);

Then look for a content somehow named XMLFiles?