Your PC doesn't recognize the iPhone 5 because you will need to install the necessary drivers, and those drivers are available within the iTunes application. The computer where you connect the device needs to have Windows or Mac.
Access the download URL to obtain an installation package: http://www.apple.com/itunes/download/
After this procedure, connect the iPhone to PC and wait for driver installation. At this point iTunes will start and the iPhone will be available. Click to show its contents (Music, Pictures, etc) then use the drag and drop procedure to get the files transferred to your computer.