Left align image on logon page

I need to add an image to the logon page. From a viewer perspective this would be the main table for the logon page, not the left column where the logon fields are but the larger area to the right. I've been asked to but an image in this space (to take up the big blank white area). I have the image configured but I can't get the image to left align.

 

Where do I configure the image alignment for the main (largest) table on the logon page?