How to Set Preview Photo To Show In Each Blog Post?

I recently went to a condensed posting on my blog, however, I can not seem to get my first photo in each post to show - which is my intention, with a snippet of the text.

Does anyone know how to correct this? I have tried everything in the custom features with no luck?

I am using VolThemes - theme is Marlin Lite.

Or- does anyone know how to just convert it back to full post view?