There's a PC version of the software you need to the download. You can find at:

Use a USB cable to connect your phone to your computer after you open the application. It will load the drivers and then try to connect to your phone. Just make sure your phone isn't passcode locked. You can then choose what you want to backup on your computer. Just make sure you don't upgrade to Windows 10. Samsung hasn't released phone drivers that are compatible with the new operating system.