CSS: header bg image position

[tonisnail]

i'm currenty developing a website, and i have a problem on the header background, so the header that i'm making is:http://i.imgur.com/h1JLm9A.jpgand currently i have this:http://i.imgur.com/LgF6HXm.jpgI'm trying to put a background image on the header, but to have the correct positioning of the image, it can not be in the header, because the image is also showing out of the header. how can i do this? i try to use z-index but don't works.html:\[code\]<div id="container"> <div id="header"> <div id="logo"> <a href="http://localhost/Yazigi/"><img src="http://localhost/Yazigi/wp-content/uploads/2013/01/logo.png" width="155" height="85" alt="Yazigi