Do you have a question about the Asus G531GW and is the answer not in the manual?
Align and insert the RAM module into the RAM module slot.
Push down the RAM module until it clicks in place.
Place the new HDD in the HDD bay, ensuring ports are clear.
Reattach and secure the new HDD with the removed screw(s).
Connect the HDD connector to the HDD.
Replace the HDD bay back in the compartment until seated.