How to add product to cart using a custom button

[NTAuthority]

Hello everybody, you may move my topic if it's in the wrong section.
I'm looking for a way to add a product to the cart when the user clicks a custom button (not the VM generated one) and when the product is successfully added the modal box should appear. I tried sending data using a GET request to the specified URL with no avail. Can anybody give me a helping hand?
Thank you!
EDIT: I've attached the code snippet I'm currently working on

[GJC Web Design]

https://forum.virtuemart.net/index.php?topic=132011.0  .. i.e. a direct link to add a product

[NTAuthority]

Thanks I'll try!