var mm = '<iframe id="iframe_header" style="width: 790px; height: 100px; visibility: visible; border: 0px; z-index:9;" frameborder="0px"  allowtransparency="true" src="http://www.ceibal.edu.uy/UserFiles/P0001/Image/portal/headerestudiantes/html/index.html"></iframe>' ;
document.write('<div id="div_header"></div>');
document.getElementById("div_header").innerHTML = mm ;