I need help transfering pictures from cell phone!!! (via USB cable & micro sd)?

I cannot send pictures from my cell phone, so I've purchased a USB cable and a Micro SD card to transfer them from my cell phone (Samsung Qwerty SGH-A687ZPAATT) to my computer (Macbook). I have the images saved onto the Micro SD, but when I plug the cell phone into the computer NOTHING HAPPENS. And, yes, it is the proper fit. I thought maybe I needed the correct driver downloaded to my computer, but I can't find one for my macbook anywhere! Help! Please!