My mom has been looking into this. I'm not sure about a website (though, I'm sure there is), as I just recently heard about it, but I know there is a facebook group for it.
A nurse practitioner put me on this in 2007 to help both lowering my weight and high blood pressure. I really liked it and did well on it but it took a bit of adjustment. My sodium intake for the day was 1500 mg and I was used to quite a bit more.
I no longer follow it as a maintainer but would definitely recommend giving it a go.
The website is dashdiet.org and if you google dash diet you find lots of other sites. One again it is the top rated weight loss diet. You can get all the information for free. It's very easy to follow.