ASP.NET displaying fixed DIV on top of page

I'm using 开发者_JAVA技巧VS2010,C# to develop my ASP.NET web app, I'm going to insert a fixed header on top of my pages so that my content area has a smaller width and these fixed DIVs are always on top of my page, in this way contents should start displaying from bottom of DIVs and not from screen top, I'm not going to use master pages, what are my options? how should I arrange my page? thanks