Subcategories inside collection

[BrittAnn]

Please help! I have a collection created for the art work I am selling.  BUT I want to have subcategories inside of the artwork collection page so when someone clicks the art collection they will be able to choose from separate categories like "Greek Mythology" or "Parks" etc.  How do I do this?  Otherwise when someone clicks the collection art, ALL of the artwork comes up. I am using the "Be Yours" THEME.

Thank you to whomever can help. 

[AfterDarkGrafx]

@BrittAnn contact the theme developers or if you feel like coding - see this - https://webpop.io/shopify/sub-collections/