I think you need a nandroid backup first - that is critical for you to be able to restore your phone to the state that it was when it was working.
Titanium backup is for backing up (and restoring) individual apps - different than nandroid backup.
You can create a nandroid backup from your custom recovery (TWRP or CWM are the more popular ones)
The first thing to do after rooting would be to install a custom recovery, and the very next thing to do would be to perform a nandroid backup. Till then, I would suggest not flashing any new ROM or changing any system files.