Build a PC, step by step
First you say what you bought, then the guide takes you through it one action at a time. Every step tells you how to know it worked.
Before you start
The manual for your motherboard and your case takes precedence over this guide. Every case is built differently, and only your manual knows which screw goes where. This guide shows the order and the place, not the details.
What did you buy?
Seven questions, all answerable by looking at your parts. After that the guide shows exactly the steps that match what you have and leaves out the rest.
What kind of processor cooler do you have?
Look inside the cooler box. A metal tower with a fan on it is an air cooler. A flat round block with two hoses leading to a grid is a liquid cooler. If you cannot tell, that is fine: the guide then shows you both routes.
Turn the processor over in its packaging. What do you see underneath?
You do not have to take it out for this. There are two designs, and they go in differently.
Is there a rectangular metal plate with many cutouts in the mainboard box?
That is the rear connector shield. On some boards it is already attached, and then none comes separately. If you are unsure, say so: the guide then shows the step to be safe.
Are the power supply cables fixed to it, or do they come separately?
Look at the side of the power supply. Rows of sockets mean the cables get plugged in.
How many memory sticks do you have?
Count the individual sticks, not the gigabytes.
What kind of drive do you have?
A narrow stick about as long as a finger is an M.2 SSD. A flat box about the size of a credit card is a SATA SSD.
Does the case already have fans fitted?
Look through the front and at the rear panel. Usually there is one at the back, and sometimes two or three at the front.