It's difficult nowadays to find a step-by-step deep down guide about TWRP, Root, and custom ROM installation process. Due to a nonstructured guide, a novice user is not able to perform the desired action.
To solve this issue twrp update comes with a strong and step-by-step guiding process about android rooting, custom ROM, unlocking the bootloader, and much more related to android.
Just read, understand and implement.