I've been through many of the d3.js tutorials and found them to be confusing. When a person is not yet very familiar with HTML and CSS, they need a bit more explanation of the details. Those details are better presented in NRecursions:
Part1: http://nrecursions.blogspot.in/2014/11/getting-your-head-around-d3js.html
Part2: http://nrecursions.blogspot.in/2014/12/getting-your-head-around-d3js-part2.html
