What I have so far

//Settings
var window = http://mc.zephyrgaming.net/Dynmap/;
var tabname = Dynmap;
var imgloc = Images/map.png;
var placement = 3;

//Tab on left side of page

//Change "tabname" to "whatever".  Tabname is what you see on the tab
var img = document.createElement("img");
//Change map.png to your own icon image.  Located in Modern/Images/
img.setAttribute("src", "imgloc");
img.setAttribute("alt", "tabname");

var span = document.createElement("span");
span.innerHTML = "tabname";

var link = document.createElement("a");
link.setAttribute("class", "sidetab");
link.setAttribute("href","#tab_tabname");
link.setAttribute("id", "tabhead_tabname");

link.appendChild(img);
link.appendChild(span);

var sidetabs = document.getElementById("sidetabs");
//change this 3 to which row you want 5th down would be 6, 7th down would be 8
var after_link = sidetabs.getElementsByTagName("a")[placement];
sidetabs.insertBefore(link, after_link);

//Page Content
//Main Div
var tabdiv = document.createElement("div");
tabdiv.setAttribute("class", "tabarea");
tabdiv.setAttribute("id", "tab_tabname");
tabdiv.innerHTML = ("<h3>tabname</h3>");
//Iframe
var tabiframe = document.createElement("iframe");
tabiframe.setAttribute("src",  "window");
tabiframe.setAttribute("height", "500px");
tabiframe.setAttribute("width", "100%");
//Second Div
var tabconents = document.createElement("div");
tabconents.setAttribute("class", "tabcontents");
//Third Div
var maparea = document.createElement("div");
maparea.setAttribute("id", "maparea")

maparea.appendChild(tabiframe);
tabconents.appendChild(maparea);
tabdiv.appendChild(tabconents);

tabs.appendChild(tabdiv);