To create an Onclick popup, please, follow the steps bellow:
1. Go to the Pages/Posts section of your Dashboard
2. Choose the Page/Post you want to add an Onclick popup
3. Click "Insert popup"
4. From the box, select the popup you need to open Onclick
5. Choose the load type, select "Click"
7. Place your cursor inside the shortcode of the popup and click Add media
8. Select your image and insert it
9. Now, Update and View the page.
10. The popup is triggered by the Image click