I really need help with this. I really don't know how to make this work. I need to populate a drop down menu with a value passed through the browser if it's passed.

so the browser URL will look like:
domain.com/?referer=YellowPagesOnline

I need to capture the referer value from the browser store it into a cookie. If the cookie is set and then populate the drop down on the page with the cookie. If it's not set then a list of sources should appear.

So I already have the code to grab the string and store it in a cookie but I'm not sure how to do the initialization of the drop down with the cookie value.


This is what I have...

Code:
<script>
//Get the referer string out of the URL
function getQuerystring(key, default_)
{

  if (default_==null) default_="";
  key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regex = new RegExp("[\\?&]"+key+"=([^&#]*)");
  var qs = regex.exec(window.location.href);
  if(qs == null)
    return default_;
  else
    return qs[1];
}


//Set the cookie for 30 days
function SetCookie(cookieName,cookieValue,nDays) {
 var today = new Date();
 var expire = new Date();
 if (nDays==null || nDays==0) nDays=1;
/* expire.setTime(today.getTime() + 3600000*24*nDays);*/
 expire.setTime(today.getTime() + (1000 * 60 * 60 * 24 * 30));     
 document.cookie = cookieName+"="+escape(cookieValue)
                 + ";expires="+expire.toGMTString();
}


//Put the cookie on the user's computer
function putcookie()
{
	var val = getQuerystring('referer');
	
	if(val !=""){
		if (document.cookie.length == 0)
		{
			SetCookie('referer', val, 1);
			alert(val);
		}
	}
	alert(document.cookie);
	
}
putcookie();




getCookie(name);

//If there is a cookie then get the cookie
function getCookie(c_name)
{

if (document.cookie.length>0)
  {
  c_start=document.cookie.indexOf(c_name + "=");
 
  if (c_start!=-1)
    {
    c_start=c_start + c_name.length+1;
    c_end=document.cookie.indexOf(";",c_start);

    if (c_end==-1) c_end=document.cookie.length;
	
if(document.SECatJax.referer.length > 0)
{	
  document.SECatJax.referer.value = unescape(document.cookie.substring(c_start,c_end));
 return false;
}
 alert(document.cookie);

    }
  }
  document.SECatJax.referer.value = 'Website'; 
}
The dropdown to appear if there isn't a cookie is
Code:
<select name="source_code" size="1" id="source_code" class="select_2" style="display:none">
<option value="" selected="selected">--</option>
<option value="Direct Mail">Direct Mail</option>
<option value="High School Presentation">High School Presentation</option>
<option value="Search Engine">Internet Search</option>
<option value="Newspaper">Newspaper</option>
<option value="Poster">Poster</option>
<option value="Radio">Radio</option>
<option value="Referral">Referral</option>
<option value="TV">TV</option>
<option value="Yellow Pages">Yellow Pages</option>
</select>
The drop down to appear if there is a cookie is
Code:
<select name="source_code2" size="1" id="source_code2" class="select_2" style="display:none">
<option value="YellowPagesOnline" selected="selected">YellowPagesOnline</option>
</select>
Can someone help me with this please? Thanks.