You can sign up for their mailing list, and after you sign up you have the opportunity to invite your friends to sign up too. In the prepared message that the website presents you with this line, "Every American has the right to organize and share their beliefs, but lately there have been an alarming number of extremists in the Tea Party who are promoting violent, racist, and hateful views." That's quite a claim to make. Oddly, the website doesn't provide any evidence in support of this claim. I think that's because the primary mission of this website is to attempt to silence the Tea Party. The NAACP, Media Matters, et al have resorted to the textbook liberal technique of attempting to smear the reputation of the Tea Party by putting up websites that claim that it's racist. Given the language of the NAACP and others on the website, you'd think that the Tea Party was some sort of re-incarnation of the Klan. Anyone with a half a brain realizes that such claims are false.
Rather than a liability for the Tea Party, I think that this website really represents a victory for it. First, the website's very existence is a testament to the sway and influence of the Tea Party in the current political landscape. If the Left didn't see the Tea Party as a threat, they wouldn't need to create such a site. But the site also demonstrates the desperation that is becoming increasingly obvious in liberal political strategy. If you have to resort to calling your opponent a racist, then it's pretty obvious your opponent has won the intellectual battle. If they're already trying to play the racist card and the elections are still two months out, then the Left is truly in a pitiful position.