I'd be happy to. Can I ask first what you've tried and what you had trouble with? I think a lot of why d3 is considered low-level is that there are lot of external things you do need to know. For example, for me, it wasn't d3 itself but functional programming that I didn't really understand. For those who don't do web development much, it might be DOM (and in particular, SVG) manipulation.

The d3 specific parts are the idea of mapping data to DOM elements (which is the part I think is beautiful), how it uses the data join to do so, and how you use the scale functions to map from data space to pixel space to set the element positions and other attributes.

Feel free to email me if you like -- it's on my profile.