What you'll have to do is host the pictures on an image hosting site, add a field to the table that you'll put the links to the pictures in. Then, in configure popup, at the bottom is a media section. Click Image, and change the Title field to list the name of the title field in your attribute table within these pointy brackets ---> {titleorwhatever}
for the url, do the same {http://urlgoeshere.com/picturethatisonlyjpgor.png}
this will put the picture at the bottom of the popup. I don't know if you can modify that to put it at the top or not. Also, good luck getting it to show up in a web app, cause I have had none.