add a gift

[niou142]

Hello i am french so sorry for my english.
I have a problem with Virtuemart.
I would like, when my customer pass an "order" higher than 100 $, to give a gift.
So i would like to write at the end of the 'order': you have a gift

but where do I add the "code" . if(...>100) etc....
and what is the syntax ?

Please I need help

Nobody ??