It wouldn't be advised for you to flash CM 10.1 to CM 10.2. Strictly because these are two different Android versions. First of all you will want to download the following links below.
(Note: This is strictly for the SGH-i747 and not the SGH-i747M variant)
After you have downloaded the above files, you'll want to flash the Clockwork with Odin. If you are unsure on how to do this, please proceed to this
tutorial. After you have flashed the last CWM, you will want to transfer the CM-10.2 image and the GApps to your root of the device. Then go into your custom recovery. Now wipe your data and dalvik cache. Then flash/install the CM10.2 zip file and then GApps. Now restart your device and you'll be on 4.3
If you are using TWRP, you'll need to find the appropriate version for that.
Samsung Galaxy S3 (SGH-i747) | Android KitKat 4.4.2 CyanogenMod 11 Nightlies
Samsung Galaxy Tab 2 (SGH-i497) | Android JellyBean 4.1.2 Stock
Nexus 7 (2013) | Android KitKat 4.4.2 Stock
Is my post helpful? It's always nice to hit that 'Thanks' button!