There are two different carriage sizes for the Hinterberg frame. Make sure you have the one for shorter harp machines. There may be info at the Hinterberg website (along with pictures of a loaded quilt, I think).
Basically you load the quilt bacing first -- on the takeup bar and the middle bar. I channel stitch the batting to the backing near the takeup bar and let the batting fall down over the backing bottom roller, inside the belly roller. The bottom of the quilt top gets attached to the belly bar (the one closest to you that can be lifted up, in which case it hits your belly, but is folded down while actually quilting). I roll the top until it is aligned with the backing/batting and channel stitch that to the backing/batting as close to the edge as possible.
Any of the Youtube videos that show how to load a quilting frame will be helpful. That's how I figured out how to load mine.
It's a good idea to join the HinterbergQuilters group and also the homequiltingsystems group on groups.yahoo.com . Lots of info in their "files" sections and old posts.