Help for Aimeos

Hi my friends, I'm looking for help.

I want to modify the way in which the price of the products is "taken", the variants can be: quantity of the product, place, etc.
please guide me where to start or if aimeos has some functionality included for this type of functionality

Greetings, I would appreciate if you help me with the following question. How can I invoke a function after making the payment? This will help me to issue an invoice