How to create a "add to cart" link on a website using magento

I want to know how to create a "add to cart" link on a website using magento.
The website of a retailer uses magento. I want to create add-in URLs to post to my Instagram. People can check directly.
Until here I came to this:
https: // domain / checkout / cart / delete / id / product /
I also found this in the source code of the page: key_form / AGXbCT8XKMhJVixv / uenc / aHR0cHM6Ly93d3cuYWZldy1zdG9yZS5jb20vZGUvY2hlY2tvdXQvY2FydC8, /