Sony PCG-XG18 Primary User Manual page 49

Remove the PC card slot protector.
When you use a Type III PC card, you need to remove both the top
and bottom PC card slot protectors.
Insert the PC card into the PC card slot, front label facing up. Gently
push the card into the slot until the card is fixed into the connector.
The RELEASE button comes out. Knock down the RELEASE button
toward the display panel.