I tried the suggestions from previous replies I saw, and nothing works!! I tried to take my 2 fingers and scroll down from the top of my phone to try what was suggested and I don't see what people are describing as the USB tab. Very frustrated!
You need to have the proper software drivers for the phone on the PC to work. This is often auto installed once the phone os connected but seems to not have occured in your case. Anyway, just download SmartSwitch from the Samsung website. It should include these drivers.