Helpful info for the somewhat-tech savvy

I admit that I don't know too much about building a website. I know basic HTML. This is why I love using Wordpress, because the templates are pre-made. I've messed around with several of them before chooising my current theme and customizing it.

Anyway, I found this very cool site that grades YOUR website! It's really interesting. It tells you what's working and what's not so good about it. It even offers a bit of advice to help make it better.

http://website.grader.com

Has anyone ever tried this? My site received a good grade, but a couple of things need some major tweaking.