|- unplug the power cord|
- lay the case on it's side
- remove the side panel
- locate the RAM slots
- insert the new stick of RAM into one of the open slots (make sure it's facing the correct direction), then press down firmly until it "clicks" in place. Make sure the locking tabs on each end are fully locked in.
Close up the case, plug it in, fire it up, then immediately enter the BIOS & configure the memory settings. Save the changes & reboot, then test the RAM using memtest86. You sure never put RAM into service without testing it first.