how to Install from 2gb to 6gb gig Ram in 2008 Imac MAC 2.4 Ghz core Duo 2 Intel chip upgrade memory - YouTube
Install memory in an iMac - Apple Support
A-Tech for Apple 6GB Kit (1x2GB + 1x4GB) DDR2 667MHz PC2-5300 200-pin SODIMM for MacBook (Late 2007, Early 2008, Early 2009), MacBook Pro (Mid 2007, Early 2008), iMac (Mid 2007) - Memory RAM Upgrade at Amazon.com