Originally Posted by GGJstudios
Just insert the RAM modules in the slots. Your iMac will come with instructions on how to add or replace RAM. It's extremely simple. Once you've installed it, just turn your Mac on and it will recognize and use the RAM. There is no "setup" process.
Did it myself this morning. Dead easy but as the others said its worth booting up with the original RAM just to check everything is running fine.
I then disconnected all connections and pushed the catch in the area where the Power Plug fits. This is quite stiff and I used small pencil to push it till it clipped free and the door on the RAM opens. You need to push two levers to the side (clearly marked) and then the RAM tray folds down a touch. As A precaution I used an earthing strap and then pulled out the two original 4GB modules. Then just locate the guides and push in the four 8GB modules and close it back up and start the iMac up again and hey presto you now have 32GB, I hope :-)