HELPPPPPPPPP!!!!!!

I don´t know what else to do!!! Well.... what else more than crying

I am doing this site for a marine company
I have validate all the HTML but I have not succeed with the CSS I have a background property wrong but I don´t know how to fix it.

And the worth thing is that I have check the site in many browsers and computers in most of the cases it look ok, but in Internet Explorer the MENU is miss up. Here is a pic of how wrong it looks.

Please HELP!! This is my final project!! I really need it some one to look a this please !!!!!

P.S. I would like to keep it strictly HTML, PHP, and CSS if I can. Thank you.

Thanks in advance....