An important note about memory is to never touch the gold leads at the bottom. Doing so can damage the module. See the image below for the proper way to handle memory.
1. Begin by unplugging the computer and removing all cables from the back. You should have an anti-static wrist strap or use a hammer to discharge yourself of static electricity because computer memory is very susceptible to damage by electric discharge.
2. Using a Phillips screw driver, remove the side cover of the computer case.
3. Next, locate a vacant memory slot on your motherboard. Some motherboards have up to 4 memory slots so be sure to check your motherboard manual for the type and size of memory your motherboard supports. The image below shows both a vacant and occupied memory slot on a motherboard.
4. Next, insert the memory module into the top of the slot. Note that there is a small notch on the memory module located on the side with the gold contacts. This notch lines up with the memory slot to prevent it from being installed improperly. As a result the memory module can only fit one way, if it does easily line up with the notch in the memory slot, try reversing the module. Also worth mentioning, DDR3 memory has the notch in the module at a slightly different location than DDR2 memory. Therefore, DDR3 memory will not fit in a memory slot designed for DDR2 memory. As a result, motherboards either support DDR2 or DDR3 memory but not both. The figure below shows the memory properly lined up in the memory slot and is about to be pushed down into place.
5. Apply gentle pressure down on the memory module evenly and the latches at the end of the memory slot will close over the memory, locking it into place. If installed correctly, you should not be able to see the gold leads at the bottom of the module, they should be fully seated into the memory slot.
6. Next, return the side cover to the case, attach all the connectors and power on the computer. After the computer loads the operating system, click on the Start icon for Windows XP users (or the Windows orb for Vista and Windows 7 users) and enter the command prompt by choosing the run dialog box and type in dxdiag then press Enter. On the ensuing screen, the operating system will tell you how much memory is present. This is a great way to check to make sure the memory you installed is recognized by the computer. If it does not show up, it is possible the memory is not supported by the motherboard or the memory is not fully seated into the slot. Below is a screenshot of the dxdiag tool with a red box drawn around the information on the installed memory.
7. Congratulations, you've just installed computer memory! Thats all there is to it!