Please help :) I need to make the custom header on my site

Please help

I need to make the custom header on my site full size and centred in-between the top bar and the menu.

I've attached a screen shot of what I mean. Here is the url... http://69.195.124.162/~totalmj8/ to the site I am talking about. The slider is on the site simply to illustrate what I want to make the header look like.

I've tried adding the following custom css which worked on the screenshot site but it does nothing on this site.

#header,
.homepage-banner {margin-bottom:0px!important;}

#header hgroup {
float: none !important;
text-align: center;
}

#header #logo {
float: none;
}

#header #navigation,
#header #navigation ul.nav {
float: none !important;
}

#header #navigation {
margin: 0 auto !important;
}

#header .nav-toggle {
position: relative;
margin-left: auto;
margin-right: auto;
}

#supplementary{background: none repeat scroll 0 0 #646464;}

Any help greatly appreciated as I am completely stuck and have just come across this forum

Thanks again

Laura