The Greenhaven Tradition YaaD course is not published on the Greenhaven Tradition website, but is made available on a person-to-person basis. Material that is not so closely held is available at http://greenhaventradition.weebly.com/
Briefly, though, I got grounding pretty quickly, got centering with some difficulty, and really struggled with shielding. It took me weeks to figure out how to shield in such a way that the shield was stable and attached to me, rather than to the spot I was sitting in when I built it. I spent a lot of time saying things like, "Look, I really suck at this, I'm clearly never going to get it right, if I can't even do this I'm never going to get through the rest of the material, and you should just fail me out of the class now."