the code should go where ever you want the message to be shown.
"where yourCart is the name of your cart object"
the if statement has the following code in it:
this references the grand total for your eCart object, but this is just an example as i don't know what you named the eCart object when you created it.
so you will need to adjust the code to use your eCart object name.
if you named the cart object "eCart1" which is the default name, the code would be: