Popup Plugin with Opacity Setting for Background

I am searching for a Popup plugin that allows for opacity control but, I can’t find a plugin that explains how to install, set the settings, add the popup window content and then HOW to add whatever gets added to the page. It seems everyone takes for granted everyone knows how to do this for the first time so there are no adequate instructions on setting up the popup and then putting whatever or however it goes onto a page or into a text container…Does it just popup somehow by magic??? Does it require a shortcode of some type??? Does it require some html or special statement in the text container???
Very FRUSTRATED!!

https://ww.wp.xz.cn/plugins/simple-popup-manager/