If you want the header section of the website to be fixed on top with menus and other information, you can simply use the below CSS to do so:
.header
{
background-color:Gray;
width:100%;
height:100px;
position:fixed;
top:0px;
margin:0px;
padding:0px;
}
body
{
padding-top:110px;
margin:0px;
}
Use it like:
<div class="header">
Header content goes here...
</div>
<div>
Body content goes here...
</div>
This can be used with Master pages too.