Awesome! I'm glad to hear that got you going.
JFBConnect will generally take the first image in the article. There are other ways to configure how the image is fetched, like by using the 'main image' of the article. If you have multiple images in the article and want to set the PinIt button to another, you'd need to add the following tag in the article itself:
{SCOpenGraph image=http://site.com/link-to-image.jpg}
That will have JFBConnect set the proper Open Graph image tag, Twitter image tag and Pinterest tag so that, when the page is shared, your custom image is used.
I hope that helps, but if not, or you need anything else, just let me know.
Thanks,
Alex