You can do it in straight
JS but I would probably use a combo of the 2 like this:
string sJavaScript;
sJavaScript += "<script language=javascript>";
sJavaScript += "window.location.opener.href='./somepage.aspx?value=" + ddl.SelectedItem.Value + "';";
sJavaScript += "window.close();";
sJavaScript += "</scr" + "ipt>";
Response.Write(sJavaScript);
--Stole this from a moderator
I will only tell you how to do it, not do it for you.
Unless, of course, you want to hire me to do work for you.