I Can't See picture when I select Post Format : Photo

Hello I need a tutorial on the different Post Formats and how they look. For now I am using the default theme which I am very happy with. I have been practicing with the Standard Post format with one picture and all looks well. But when I select the Photo Post Format for the same post, I can no longer see the picture.. just an empty white space... Not sure what I am doing wrong. I would like to see how this photo format differs from the standard post format, but I first need to solve this problem of why the photo is disappearing. Thanks for any assistance

Regards
Scott