Step 2: Imitation is the most sincere form of flattery.
Step 3: Is your life truly ruined by this ?, if not, see steps 1 & 2, if so, see step 4.
Step 4: Follow youtubes example, insist that your Govt brings in a minimum of 10 years jail for posting 'copyright' material. That should give you something else to do !
You did copyright your skin didn't you ?
Seriously, does this really matter ?
Of course, I assume you've NEVER leached anything off the net yourself or ever done anything that's illegal, like speeding or any other activity that's illegal in your jurisdiction, if so, please turn yourself in first.
Depending on how much modified in US courts you can sue. However for internet cases you normally can't sue unless you have loss of profits. Like if someone attacks 500Server's they can record the proof of income loss and sue whoever arranged the attack, if they knew their info.
Regardless you'll need a lawyer unless you can write formal DMCA notices. I provide webhosting, I have to deal with those things. If the other person identifies errors in it, you'll be eligible to be sue'd for falsified DMCA notice. This is not a joke.