How to install custom ROM on Samsung Galaxy S4

Step 1 : First of all download a custom rom which you want to install on your Samsung Galaxy s4 , After you download the .zip to your computer, plug in your device via USB cable.  Copy the .zip file to the SD Card (do NOT extract it, just copy the whole zip file). Unplug your device.

Step 2 : Now, Power off your device and go to the recovery mode by pressing  and holding down the Volume Down, Home and Power buttons together

Step 3 : Once in recovery mode, use the volume buttons to navigate and power button to select .

Step 4 : Then select Backup and hit yes to confirm. Wait for it to finish backing up your current system (this will save you if something goes wrong).

Step 5 : Select Wipe Data / Factory Reset.

Step 6 : Select Flash zip from sdcard.

Step 7 : Select Choose zip from sdcard , find the ROM you copied to the sdcard in .zip format and select it. Then select yes to confirm. Wait for it to finish flashing.

Step 8 : Now Select Reboot System Now. Once it reboots (which will take a while the first time), you’ll be running the new ROM .
Congrats !