does this dropdown list using ListItem or just regular array? Assuming it's an ArrayList, you can check case by case as follows (the code can go in the code-behind for the button click event)
If ddlIdName.SelectedItem.Text = "1" Then
lblMessage.Text = "god"
ElseIf ddlIdName.Selecteditem.Text = "2" Then
'change the color of the label to red
I don't know if this is what you were asking....