Sorry, by the time I read you original post, on my phone, and went to my computer to answer, I forgot you said you were on Moodle 1.9. I haven't used my Moodle 1.9.19+ for a while but you still should be able to do the background image in a table. It is just a little more trouble to get it to work.
Create your table. Go back in to edit and swtich to the larger/full screen editor mode that gives you the extra row of editor toolbuttons. The first button in the new row is table properties, click in your table, then click the table properties toolbutton. In the bottom section under Style [CSS] there is a place were you can add an image URL Theimage will get tiled to fill in the whole background of the table.
Hope it works for you,