Download Samsung Kies for Samsung Galaxy Core GT-I8260 From This Direct Link, Resume Supported.
After Downloading the Samsung Kies software you have to install it into your Computer before connecting your device, So all you have to do is installing it like any other windows software or program, Restart the computer then connect the device to it using USB cable.
After your computer detects the device and installs the need driver for it, You can manage everything in your device like messages, Contacts, and much more.
In case this is the first time you know this program then here is a great link to learn more about How To Use Samsung Kies.
Notice: This Software support all Windows versions and Mac OS too, Also in case you do not have a USB driver for your device then this software has it, Just install Samsung Kies and all needed USB drivers will be installed too.