Filterable portfolio link to url

I have a portfolio section on my website that can be filtered to show the different categories. ( https://www.thegoodfoodandwinecompany.co.uk/index.php/products-2/)

When you go to that page you can choose All, Artisan Range and Hamper Range. I would like to create a drop down menu with Artisan range and Hamper Range that just gives those products but i can’t see any url to create that – basically if you click on the links it keeps the same url but calls #filter

Any help would be greatly appreciated

Thanks