Be sure computer is unplugged, turned off, and battery is removed.
Then, locate memory door and remove screw with #0 Phillips screw driver.
If needed, pry open door using knife or flat screw driver.
Remove plastic door to expose lone memory DIMM.
Press two metal clasps on both sides of the DIMM apart to allow memory module to pop up.
Head over to Newegg and buy yourself a 2gb DDR2, 667mhz laptop memory to install in your Aspire One.