Bro, as you're a beginner I'd advise you not to flash a custom ROM now. Especially not Wanam.
Go to sammobile and search I9505 in the firmwares section. Download any 4.4.2 firmware with any country but if you want a black edition ROM, then click on the ROM that shows (Black Edition) in brackets.
OR
Unroot your phone. Do a factory reset, device status will change from Modified to Stock/Original. Then search for update via OTA and update your phone to KitKat.
Just letting you know, I'm not a noob. Have owned 6 Samsung devices before. My Xperia Z is my second Sony device in my history of Android devices. 
If you need further help, PM or WhatsApp.
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