this picture is taken from underneath the laptop, i had once a Mtac laptop on my desk and replaced the CD-ROM with a DVD-CD-ROM and if memory is correct, the RAM sits somewhere below your "Y" key just below the keyboard.
Take a fine screwdriver and place it between the F1 key and the frame and tilt it slightly, that releases the little notch there, the same procedure at the INSERT key and the keyboard comes off...
There may be a protective alloy sheet screwed to the laptop below the keyboard, remove it and there you should see the RAM.
I assume you guessed already that the Notebook should be switched off...