Make sure the Electricity is turned off - and unplug all devices plugged into the Mac.
Just follow the instructions from the manual and you will be fine; you should however really leave the Mac plugged in to the electric supply -
but switched off, when doing the install, this gives a better ground/earth to get rid of any static, you should really get yourself an
anti-static wrist band, but failing that
(before taking the ram out of the silver anti-static bag that it comes in) touch the case of the power supply or anything metal inside you Mac , this should get rid of any static electricity, then open bag and pop in the ram.
Once the Ram is in, and the case is back on, just boot it back up, and have a loook under the Apple menu, about this computer, if the Ram is there, then you are all done. Nothing else to configue, true plug and play !
If your computer won't boot open back up, (touch metal again-get rid of static!), check that the Ram is seated correctly, if not take out and put back in.
Replace case etc.
If still no boot take out new Ram, reboot check computer will boot without new Ram.
Take out original Ram from slot One and replace with new Ram, reboot etc
If no boot, chances are Ram is fried, doesn't happen very often, so don't worry.