how do Credit Cards work when buying something online

hiii, i don't own any credit card atm and i wanted to purchase something expensive. gusto ko lang malaman if im going to buy something online (lets say about php 30,000); and i pay using credit card, pano yung process ng monthly payment for that 30k or is it even going to be a monthly payment? sorry huhu naguluhan lang ako when i asked someone about it. akala ko that's how it works. (pls be nice it's going to be my first grown up purchase sana wshagsha)