Shopify Masonry Collections Tutorial

I need to be able to add custom filters on the Collection Pages that will show on the drop down menu. Specifically the "Category" menu. I know the option exists, but I cannot remember how to do it. Long story.

Need to add "Special Occasions" to the only Collection currently published. Then a .doc/.txt explaining how to do it exactly.
I have attached a screenshot showing the current page.


If you know the Masonry theme inside out and can explain things clearly in real time, let’s get this booked in.