Added a Custom add_to_cart button... How do I make it function?

[simlulu]

I opened "product-card.liquid" and searched for "price_class" and edited it from:

{% render 'price', product: card_product, price_class: '', show_compare_at_price: true %}

to:

{% render 'price', product: card_product, price_class: 'button button--full-width button--secondary', show_compare_at_price: true %}

and so I got this button to display underneath my Product Image. The only problem is that it doesn't function how a "choose-options" actually does. Kindly help me out here my brain cells are about to explode!