I am working on a niche store, and I need to add some add on items while clicking on the add to cart button. So whilst clicking on the add to cart button, it generates a pop-up and on the pop you can select you add on item(s) and after selecting the item on the popup, it also add its to the total price.
I'm not a developer, but I found a website doing what I want. So I have the source code for popups, copied from a website, which is product specific and not general. I also have the design of the specific page but again not for the whole website.