Automatically add "more" after image | CyberSEO Pro | Support Forum

My blog is configured to pull posts, all of which has an image and the content after the image. 

I don't know a thing about coding, so I need some help. How do I add some php code that automatically add a <!–more–> tag after the image, so the content is hidden and only the images are displayed on the blog homepage so users have to click through to access the posts?

Thanks in advance.