Installing Rom via TWRP recovery

View my before post for how to flash twrp recovery...
your android device should have a root access.
1. open recovery mode
2.select wipe


 

3.and select the above picture shown icon and wipe it
4. now go back and click install and do as below in picture

5. as above picture select your rom is sdcard in your device and swipe to install your costume rom,,
     note:: after rom installation completed do wipe cache clean and reboot your android device.