Unlocking your bootloader will almost certainly void your warranty. If your phone is still under warranty, you'll need to decide if the benefits outweigh this loss.
What is your for the upgrade? (Better speed, newer Android version, or more features?) Is your Nokia C100 carrier-locked or factory unlocked ? nokia c100 custom rom better
Do you have any prior experience with or using flashing tools ? Unlocking your bootloader will almost certainly void your