custome module

hi all
i am net to open cart so how can i create custom module i need following two module kindly help me in this thanks in advanace
need to add module in between
when customer chooses a product to add to cart,
a window opens up with questions , once he answers them, he will be suggested weather he should purchase this iteam or consult the doctor.
so we need two modules..
one is question and optional answer module
and another is consulting doctor module associated with category.

thanks and regards
keyur

I can perhaps help you out with this. PM me the details in a bullet list fashion and I will reply.