Often the digital link between the camera and computer is intentionally one-way, camera -> computer only. Maybe you should study the camera manual carefully? And the documentation that comes with the camera software? However, whether or not you are able to write to the camera using the cable, I suggest you buy a USB card reader suitable for the type of card in your camera. They are not very expensive. Then you can take the memory card out of the camera, insert it into the reader, plug the reader into a convenient USB port, and it will act as a removable drive with two-way access. The speed of data transfer is usually much higher than via the cable.
Note that larger SD cards (4 GB+) may be to the newer SDHC standard so making sure any reader you buy has this capability might be a good idea.
you could address a flash memory card on a digital camera and effectively save other types of data onto it, besides digital photographs - just like a thumb drive.
A memory card inserted into a USB reader, is, in effect, a pen drive, one with detachable, interchangeable memory.