Aperture-Question about folders/projects

[RONE]

I currently have a bunch of pictures from some races I took last month divided by person into separate projects. I'd like to have them all combined in one project, but still separated into easily discernible folders by person. Can someone please explain the folder hierarchy that Aperture uses to me?

Here's what a small portion of my library looks like now:

I'd like to combine all the "2007 HPT Races" projects into a single project with sub-folders, but I'm unsure how to do that.

 

[RONE]

In case anyone else later searches for this info:

I am using smart galleries based on keywords. I added each person's name to their picture, then moved all the individual photos into a single project, then made a smart gallery for each person.