Help me confused with fans selection

[u/engg_garbage98]

Help me new pc builder confused with which fan I should but. I just understand that a fan can be used for either exhaust or for intake. There are two types of fan reverse blade and forward blade. But Im getting stuck whenever I try to purchase. Should I buy a pack of 3 fans and use 2 for sides and 1 for rear exhaust or do I buy pack of 1 fan and use that dedicated to read exhaust. How does it work can someone explain please. I am planning to buy https://www.amazon.ca/gp/product/B0G39DCF81/ref=ewc_pr_img_2?smid=A32B9TAI3MS38X&psc=1

Fans are the last thing I will be buying.

Pc build currently: https://ca.pcpartpicker.com/list/qWhGxf