First you open the case,lay the case in your work area and remove the side panel that provides access to the interior. For most cases, this means the left-side panel (as viewed from the front). Also remove anything that is dangling inside the case, or if it is attached, push it aside. Many cases have permanent internal wiring that can become a hassle later.
Know where to buy components. In-store locations such as Best Buy will stock computer components, but you can usually find comparable parts for cheaper if you shop online. Common online locations include Amazon, eBay, and NewEgg.
Assembling Your Computer.Use an antistatic wrist-strap cable to prevent electrostatic discharge (ESD) which can be deadly to computer electronics. Alternatively, touch a large metal body like a radiator to discharge yourself.
Running Your Computer.Using your power source's power cable, plug your computer into a wall outlet or power strip.You'll typically use the graphics card output that's near the bottom of the case, though some motherboards may have this port on the right or left side of the case.Press the computer's Power button titled Windowspower.png button on the front or back of the case. If everything's properly connected, your computer should start up.