How can I add submenus to a menu item for different collections?

[TheUnavailable]

Hi, currently there’s a 'Shop' section in my navigation menu, and once clicked it shows all products, but I want it to be separated by the core and the premium collections.

I want the 'Shop' in the menu to have an option when it's clicked to show 'Core Collection' and 'Premium Collection' rather than just showing all products.

https://theunavailable.myshopify.com/

Thank you. 

[suyash1]

@TheUnavailable - I think you have changed it, you have 2 collections on that page now