Ahhh a question carefull I might start feeling important lol, hey but I have no clue on CSS I have seen it I have read about it but I want to get The HTML under control before i jump in the next stage.
I am trying to get a grip on the html and the tables, I have heard pro's and cons about them so i guess personal pref.
The css I will start learning that because I understand it makes a lot of things quicker since you dont have to repeat yourself over and over, just write the css part and call it again later or something.
But for now ill stay with my learning the html.
as far as your question about the image, it will not cover up the content of the table since the only content of that table is an image
the first image is as wide and high as the table the 2nd is a small animated gif file with transparent background ( a pointer) this will point at a certain section of the 1st image
hope this makes my idea clear.
better yet I hope this can be done.