Here are the steps for flashing ".tar" files using Odin. Keep in mind that along with risking damage to your phone, you may be voiding your warranty. The responsibility for any damage incurred by following this guide is yours and yours alone.
NOTE: These instructions are for PC only. They will not work for Mac users.
Download desired ".tar" or ".tar.md5" file and place somewhere on your PC where it can be easily located.
Download Samsung drivers from HERE.
Download Odin (computer program) from HERE.
1. Install Samsung drivers on your computer.
2. Open Odin on your computer. (You may need to disable antivirus programs on your computer and/or phone for this to work properly.)
3. Power off your phone and remove the battery.
4. Plug the stock USB cord that came with your phone into a powered USB port on your computer (usually on the back of the CPU).
5. Press and hold the "volume down" button on your phone, and continue to hold it while plugging the USB cord into your phone. This will put your phone into download mode. You'll see a large yellow triangle on the screen of your phone. (Let go of the volume button at this point.) You will also see one of the small boxes in Odin turn yellow, as well as "Added" appearing in the message box.
6. Click the PDA button in Odin (NOT the PHONE button) and navigate to the ".tar" file you downloaded earlier.
7. Click START. When this process has finished, you'll be notified in Odin (succeeded 1 / failed 0) and your phone's screen will go blank.
8. Unplug your phone, re-insert the battery, and power on. At this point your phone should boot up with the desired changes.