Follow the instructions to create an Image popup:
1. In your Dashboard, find Popup Builder plugin and click "Add new" popup
2. Select the Image popup from your menu of popup types
3. Enter a Title for your Image popup (it's visible only to the Admin)
4. Select and image from your popup - paste the URL of your image or choose from your gallery.
5. Select the theme for your popup (if you need no borders for your popup, select the 2nd theme)
6. Setting up the Dimensions of your Image popup, the best option to have a responsive popup is to use the "Responsive mode" with the Auto option for your popup dimensions.
7. Otherwise, in the Custom mode of the Dimensions, you can set the Dimensions of the popup according to the dimensions of the image you want to have in the Image popup. (in %)
Here's how our Image popup looks like. (Example)
Check the following article to redirect users on the Image click: How to redirect users after clicking on the popup image?