Graders were one of my favorite machines to run just behind excavators, mainly because I could actually cut a good grade with them unlike dozers where the blade is out in front and you can get rocking back and forth and do what we called fancy dozer work. That's when you've got bumps all over the place and the boss hollers "never mind that fancy work, just make it level".
As Thomas suggested , weight will definately help. I can't quite tell from the photo but it looks like you can adjust the tilt with the link on the rear axle which will help to build the crown in the center. As far as length, the general theory as I always understood it, is the more length the better, as it will bridge further over any crowns to take them out and fill in the hollows over a longer area.
You've probably already discovered you can't cut much at a time. To start you can run through with a straight blade cutting lightly to discover where your highs and lows are. When you get them pretty well filled, start at the edge of the road and wing toward the center with a light cut. That action of the material moving across the blade fills any depressions the straight blade didn't get and the loose material in the resulting windrow will easily wing across on the next pass. You may have to move the material back and forth a couple times until you're satisfied that it's smooth enough. For any leftover windrows, just raise outside blade edge a little and lose it. There is one problem with working the grade too much though and that is segregation. The larger stones will tend to come to the surface while the fines settle and unless you have a really good roller, you may get what we call raveling, where the stones get kicked off by traffic and you get an uneven surface again.
It's very hard to tell anyone how to grade, it's more of get out and do it until you learn how.
Hope this helps.
Smiley
