If you are coming from Rooting Guide for One X, this guide helps you to flash a ROM on HTC One X.
Before you begin please backup your current ROM to preserve data in case of unexpected failure.
How to flash a ROM on any Android Phone:
How to backup your current ROM and all system data along with apps and settings ?
Restart your device from power menu while holding VOLUME DOWN button or press both POWER and VOLUME DOWN simultaneously.
You will enter Bootloader mode. (A white screen with three Android robots dancing)
Now press VOLUME DOWN to highlight RECOVERY mode and press POWER to select.
You will enter the recovery menu after a short restart.
The recovery menu has an option “Backup and Restore”, highlight it using VOLUME buttons for up-down navigation and press POWER or tap it to select(works only if using a Touch recovery like ClockWorkMod touch recovery).
Then select Backup(press POWER or tap)
Confirm by selecting “Yes, Backup”.
Wait for the process to complete. It should ideally take less than 5 minutes.
When you see a successfully completed backup message, you are done with backup that can restore your system data including contacts, sms, mms, bookmarks, settings, apps, app data and settings and everything else on your device as it was during the backup.