EDIT: I am adding what I saw in the pic you provided. I believe the loose pieces sitting on top are slate bed pieces. They should fit together like a puzzle on the frame and screw down to it. The slate should lay on top of those. I'm pretty sure about that, but not 100% without more pics. By the way, let me know if you want me to finish my little guide here and if you want, if you post pics of all the parts, I could certainly tell you what they all do and where they go. Even the hardware. So, with that being said, let the fun begin. BTW, I stopped typing because I ran out of time..........................................
Okay, I'll give this a shot.