How to flash a custom rom on galaxy on5 pro I'm an Android fan and I have a Samsung Galaxy On5 Pro.
It is currently running Android Marshmallow 6.1.
I want it to get upgraded to Android Nougat 7.1.1.
I don't have a recovery.
How can I install TWRP?
How do I do it?
Edit:
I got TWRP and installed android nougat 7.1.1
How do I install android 8.1?
Root your device at your own risk!

Check your device model number. (for SM-G550FY/SM-G550T1/SM-G5500T2/SM-G5500 only)
Select TWRP Based on the mobile model number.
Make sure your device battery is charged above 50%
Backup your current files and data, just in case (save them on external storage).
Flash TWRP using odin
Install SuperSU.

For detailed information see https://www.androidinfotech.com/root-samsung-galaxy-on5-sm-g550-lollipop-marshmallow/ and https://rootmydevice.com/root-samsung-galaxy-on5-pro/