1. Turn your Sony VGN-CS390DBB laptop over.
2. Find the laptop battery release button lock for your Sony VGN-CS390DBB laptop.
3. Now that your Sony VGN-CS390DBB laptop battery is unlocked, find the battery release button down.
4. Holding the laptop battery release button, gently pull your battery away from the laptop.
5. Now that your Sony VGN-CS390DBB battery is removed, grab your replacement Sony VGN-CS390DBB battery for installation.
6. Insert the battery into the slot. Push the Sony VGN-CS390DBB battery towards the laptop and secure it in place.