Nelle proprietà della dropDownList:


myDDL.AutoPostBack = "True";
myDDL.OnSelectedIndexChanged = "CuteDDL_SelectedIndexChanged"




protected void CuteDDL_SelectedIndexChanged(object sender, EventArgs e)
{
if(myDDL.Text == "ciccio_scarica")

// potresti fare un Response.Redirect(~/pdf/ciccio.pdf);

}