How to connect my Nikon D3100 to my computer?

I have the recommended USB and have installed the software. I'm working on a Mac and I know it should show up on my Desktop. But nothing is showing up. Why not and how can I fix this problem?

Added (1). Edit: Thank you, everyone. I'm going to pick up a card reader. I've also figured out the problem. The USB may not have been the right kind, even though it fit in my camera. I found a cable that works for now, but I will definitely be picking up a card reader.

Make sure that the you turn the camera on after attaching it to your computer. Use Finder to see the connection to your D3100

Actually for nearly a decade, those of us who have been using digital cameras have used either on-board card readers on our computers or use a USB 2.0 (3.0 now) card reader and avoid using the connection between the camera and computer.

Using a card reader is faster for copying all the image files to your computer, to a new file folder you create that indicates the subject and date taken. Sample: River022012.

It also allows you to continue using the camera (and a second memory card) while the images are being copied to the computer. This is what happens as part of the workflow in the studio. While the photographer is shooting products, their assistant can be copying images from used memory cards to the office computer

Have you tried to use a Card Reader? Using a Card Reader makes downloading photos onto the computer so much easier. Plus Card Readers can be used on many different types of computers and No Software is needed to run the Card Readers.