How do I make buttons on my page open a form or checkout pop up?

1. Create the pop up in your website and put the form or payment form in it.
2. Select each button on the page that should open it and set the button's link to that pop up.
3. Test every button to confirm the pop up opens.

Keeping the form in a pop up on the same page, instead of sending visitors to a separate form page, keeps people from dropping off.