Get stock firmware for country/carrier from Samfirmware (not 4.0.4 if you intend to root your phone in the future), flash with Odin in download mode. How ? Thread stickied near top of Q&A titled 'Flash stock firmware' has instructions. Problems with Odin flash ? Hopper8's 'Odin troubleshooting' thread stickied in General section has all the info you need to get a successful Odin flash & a 'clean slate'.
As to how instructions on another site will/won't work, no idea & won't be looking at those.. Not interested in what's on other sites given most of the info found on them has probably been posted here in the first instance anyway. You don't need other sites when you have a resource like this one at your disposal.
Once you're back at stock, you can then re-root your phone & flash whatever custom rom/kernel you want again (maybe not do that until you're totally comfortable with whatever process you need to use first).
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?