One caution about installing the RAM yourself: Be sure you are grounded when you do so, or you could damage the motherboard by releasing static electricity. You can ground yourself by keeping your wrist or some other part of your body (no, not that part

) firmly placed against the power supply while installing the RAM.
If you have lost your manuals, you can also find out much of the information you need regarding upgrading your RAM from the computer manufacturer's web page. I bet if you post the MFG and the complete model number from the back or bottom of the computer, someone here could tell you the answer to many of the questions posed in earlier posts.
Good luck.