Create some pop ups

on this page (mobile view) https://staging5.acupuncture-in-bath.co.uk/dna-testing-for-fertility/# I have 3 places where is says read more/learn more in brackets and I want popups (all the same) to appear when they are clicked so as to stay on the page. I can add the content later but I need space for a logo, I just don't know how to make the popups. They need to be white and you could add a sample logo and so text to make it easier for me to replace it with mine. It needs to look nice.