Shopify Cart Customization -- 2

I want to add 2 drop-down fields in the checkout page of my Shopify store and some functionality with the shipping fee. It should have:
- one Dropdown field having a list
- another Dropdown field that depend on the option chosen in the first drop-down list
- The Dynamic shipping fee should depend on the first list to be added

The shipping fees should depend on the selection of the first dropdown list. Thanks