First of all you need to have your mobile phone charged. It should have atleast 80% charge remaining.
Enable USB Debugging on your phone from Settings –> Manage Applications –> Development –> USB Debugging.
The most important one: Back up all your important data like contacts, SMS, emails etc.
Download the latest USB Drivers for your Android Device from manufacturer official website.
Done? Ready to start the installation process? Well, go through the simple steps below:
Connect your phone to your computer via USB cable and copy the downloaded zip file to phone SD card.
Now Turn OFF your S4 I9500 and get it into recovery mode by pressing and holding “Volume Up + Home + Power Buttons” for few seconds until you see Android logo.
Now in recovery mode, select “Wipe data/Factory reset” option first so the previous ROM is deleted.
Now select the “Wipe Cache partition” option to wipe the cache.
Go back to main recovery window and select Advance and then select “Wipe Dalvik Cache” to perform Dalvik cache wiping.
Back to main recovery window again and this time select “Install ZIP from sdcard” followed by “choose zip from sd card” and browse for the transferred zip file.
Now installation of CM11 Android 4.4 KitKat rom will get started. Once the installation is finished, reboot your phone and please note that your phone might get more time to boot for the first time after rom installation so nothing to worry about.
Successfully installed CM11 Android 4.4 KitKat rom on Galaxy S4 I9500? If yes then enjoy otherwise let me know about your problem in comments so I can help you out.