There's this site that's stealing my content and I'm trying to get in touch with him but couldn't find his email anywhere.. I even tried domaintools to trace him but he set them to private. What's the best way or how can I communicate with him?
You may have to skip contacting the webmaster and go straight to his hosting provider. If it's a US host, there should be instructions on how to file a DMCA complaint with them.
Just a thought... but you could try sending an email to admin @ whatevertheirsiteis.com or webmaster @ whatevertheirsiteis.com and hope that their catch all email delivers your message to them.
Send a complaint to the registrar of the Domain name. They should be able to tell you how to take further actions.
With private whois, the domain provided (if whoisgaurd), will redirect to emails to their email. Anyhow, most likely just posting from RSS feeds, will be banned from google soon so you don't have to worry about it for a long time, those kinds of blogs don't last long