You can in an HTML widget, but the HTML in the RTE in a doc/discussion/blog post is more restrictive and will not allow it. Now, maybe you can adjust settings in admin, but I don't know.
In the HTML widget I created a table and made the column background a picture. That works. But not in the RTE.
I with the RTE didn't have such limited HTML capabilities.
I was able to right click on the image to adjust alignment but I am reminded that Jive is a collaboration tool and not meant for supporting graphic layouts. We will leave that to Adobe products. I like your idea of stylizing a table and incorporating graphics into that.