Detailed guide:
1. Push the clip on each side of the RAM slot.
2. Pull the old stick out, vertically upwards.
3. Push the new RAM in until the clips at either end click back into their original position automatically - this might take a little force, so make sure you support your motherboard from the underside to avoid cracking it. Make sure the notch in the RAM slot is aligned with the little gap on the bottom of the RAM stick.