This is a full-on fleshed-out how-to video on installing a PSU in a PC. It’s not gonna be a short one, just warning you off-the-bat, but basically it’s all the ins and outs of a power supply, what you need to know, what every cable is meant for and what goes where. It’s actually very simple if you’re new to it.
Please do not ask me what kind of PSU your PC should have, look up the specs of the parts you’re getting and go from there; there’s simply too much information to know beforehand and I cannot respond to every single comment with vital information. Thank you.