WordPress menu fixed, how to?

This is my wordpress menu css:

/* 2.2 Navigation */
#navigation-outer{background: #FCFCFC url('images/footer-widgets-bg.jpg') repeat-x left top; margin-bottom:10px;}
.single #navigation-outer,.page #navigation-outer, .archive #navigation-outer {
	margin-bottom: 0;
}

#navigation-logo {
background: transparent url(images/turismoin.logo.png)
left no-repeat;
}

#navigation{font:12px/12px Helvetica, Arial, sans-serif; margin-left:115px;}

.nav { width:1000px; z-index:99; margin:0; padding:0; list-style:none; line-height:1; }
.nav a  { position:relative; color:#fff; display:block; z-index:100; padding: 8px; padding-right:19px; padding-left:19px; line-height:29px; text-decoration:none; font-size: 12px; }
.nav a:hover, .nav li.current_page_item, .nav li.current_page_parent, .nav li.current-menu-item, .nav li.current-category-ancestor,  .nav li.current-menu-ancestor, .nav li.current-menu-parent{ background:#439EF8; }
.nav li  { float:left; width: auto;}
.nav li a.sf-with-ul { padding-right:30px; }

/* 2.2.1 Drop-down menus */
.nav li ul  { background: #414448; position: absolute; left: -999em; width: 200px; z-index:999; }
.nav li ul li  { background:#414448;}
.nav li ul li a  { width:180px; color:#fff; padding: 5px 10px }
.nav li ul li a.sf-with-ul { padding:5px 10px; }
.nav li ul li a:hover  { background:#439EF8;}
.nav li ul ul  { margin: -30px 0 0 180px; }
.nav li ul ul li a  {  }
.nav li ul li ul li a  {  }

.nav li:hover,.nav li.hover  { position:static; }
.nav li:hover ul ul, .nav li.sfhover ul ul,
.nav li:hover ul ul ul, .nav li.sfhover ul ul ul,
.nav li:hover ul ul ul ul, .nav li.sfhover ul ul ul ul { left:-999em; }
.nav li:hover ul, .nav li.sfhover ul,
.nav li li:hover ul, .nav li li.sfhover ul,
.nav li li li:hover ul, .nav li li li.sfhover ul,
.nav li li li li:hover ul, .nav li li li li.sfhover ul  { left:auto; }

.nav .sf-sub-indicator {background:	url(images/arrow-superfish.png) no-repeat;position:absolute;display:block;right:1em;top:1.6em;width:10px;height:10px;text-indent:-999em;overflow:hidden;}
.nav li ul .sf-sub-indicator {background:url(images/arrow-superfish-right.png) no-repeat; top:1em;}

If i add position:fixed the menu go to left. How to use a div used for wordpress bar? What is the best solution for you?
Thanks in advance.
Best regards!