You should always "format" a new card in the camera that it will be used in. Look thru the menu of the camera and you should find the key or command to format the card while it is in the camera. You can also format the card in your computer. Go to this link and follow the steps.
Of course you need to format the card. But also check to see if the slide switch on the side of the card has been slid to prevent the card to be readable only. You can also run a memory check chkdsk on your computer to make sure your card does not have any damage.