Unplug the power cable. If you need to move the computer to access it easier, remove all the cables from the back. Place the desktop on its side somewhere that gives you easy access. Lay it down with the ports on the back closest to the table. Some cases have thumbscrews for easy opening, while older cases typically require a Phillips head screwdriver. Slide the panel off or pull it open after removing the screws. Make sure to remove the panel that allows access to the motherboard. You can determine which panel to remove by looking for the I/O ports on the back of the computer. These ports include monitor, Ethernet, speaker, USB, and more. They are connected to the motherboard, so remove the panel on the opposite side. Anytime you work inside a computer, you risk emitting an electrostatic discharge that could damage your components. You can reduce this risk by wearing an anti-static wriststrap, or by grounding yourself before working in the computer. Touching a metal water tap will ground you. If you are replacing RAM, pop out the old modules by pressing down on the latches on each end of the module. The RAM module should pop out of the slot, allowing you to lift it directly out. Many motherboards have four slots for RAM, but pairs are typically not installed directly next to each other. For example, the slots may be laid out as A1, B1, A2, B2 and you would install your first pair on A1 and B1. Refer to your motherboard documentation to ensure that you know which slots to use. If you don't have your documentation handy, you can often tell which slots are pairs by looking at the coloring. They may be labeled on the edge, which each label etched onto the motherboard. These labels may be small, so you may have to look closely. Push each module directly into the slot, ensuring that the notches at the bottom line up. Apply even pressure directly to the top of the module until it is inserted and the latches snap into place on each side. Do not force the modules in or you may break them. Nearly all RAM is installed in pairs. Some computers will have difficulty with a single RAM stick, and using only one stick will decrease performance.    {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/28\/Add-RAM-Step-12Bullet1.jpg\/v4-459px-Add-RAM-Step-12Bullet1.jpg","bigUrl":"\/images\/thumb\/2\/28\/Add-RAM-Step-12Bullet1.jpg\/aid1606556-v4-728px-Add-RAM-Step-12Bullet1.jpg","smallWidth":460,"smallHeight":306,"bigWidth":"728","bigHeight":"485","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a> (screenshot)<br>\n<\/p><\/div>"} With the RAM installed, close up your computer and screw the case panel back into place. Plug all of the cables back in. Turn on your computer and allow it to boot into your operating system. You may be prompted to continue due to your new RAM installation. If your computer runs into a serious error at this point, the RAM may be improperly installed, or there may be an errors with one of your new modules. See this guide for instructions on testing your RAM modules. Open your computer's system information to verify that the RAM was properly installed and is being used. Double-check that the amount is being displayed correctly.  Windows - Open the System Properties window by pressing ⊞ Win+Pause. Verify your installed RAM in the System section. Mac - Click the Apple menu and select "About This Mac". Verify your installed RAM in the Memory entry.

Summary:
Power down the computer. Open the case. Ground yourself. Remove existing RAM (if necessary). Check how the RAM slots are laid out. Install your RAM. Close up the computer. Boot up your operating system. Verify that the RAM is recognized.