Here’s the How To steps:

Find out how much RAM your computer has.
To find out how much RAM you have in a PC or laptop that is running the Windows operating system, right click on the “My Computer” icon on the desktop or the start menu, and choose “Properties”.  On that page you will find how much memory (RAM) your computer has.

Find out what type and how much RAM your motherboard will accept.
That same “Properties” page will also tell you the manufacturer and model number of your computer, unless it’s a generic type computer, then it will only tell you the CPU type and speed.

If you know the manufacturer and model number of computer:
Look in the book you received with your computer to determine the type of memory you need and how much you can add.  If you no longer have that book, then you should be able to find the information you need from the support section of the computer manufacturer’s website.

If you have a generic computer or don’t know who made it:
Remove the cover and look on the motherboard itself.  You will find a model number printed somewhere on the top of it, usually close to the center and in bigger type than everything else.
Sometimes you will find the manufacturer’s name, but not always.  If you find the manufacturer’s name, go to their support website and find the owner’s manual/spec’s for that motherboard model number to find out how much and what type of memory to install.
If you don’t find the manufacturer’s name, do a web search for the model number and look for the manufacturer’s website there.

If all else fails:
Open the case, locate the existing RAM card(s)  (a small circuit board approximately 5″ long by 1″ -- 1.5″ tall, plugged in perpendicular to the motherboard), and count how many slots there are total that are the same size right next to it.  Then push the tabs on each end of the card to remove it, and take it to your local retailer and tell him “Give me some of these, only bigger.”

CAUTION: ALWAYS BE CAREFUL WHEN HANDLING COMPUTER COMPONENTS -- STATIC ELECTRICITY CAN EASILY HARM OR DESTROY SOME OF THE CIRCUITS.  ALWAYS REMOVE THE POWER AND GROUND YOURSELF (TOUCH THE CASE) BEFORE TOUCHING THE ELECTRONICS, AND USE ANTI-STATIC PACKAGING FOR STORAGE OR TRANSPORTATION WHENEVER POSSIBLE.

Installation:
Once you have removed the computer cover and located the RAM slots, make sure the clips on each end of the RAM slots that you are planning to fill are pulled back.
Line up the slot on the contact edge of the RAM card with the key inside the motherboard RAM slot.  It is slotted to prevent installing backwards.
Place the card in the slot and press firmly.  You will know that it is locked in when the tabs raise up and lock into the slots in the end of the RAM card.
Replace cover, hook up computer, and you’re off to the races!

Disclaimer: Eveything on this website is for my entertainment only -- If you screw up and break something or hurt yourself, you’re on your own.