Take all those measurements and decide how big your bed will be and how high you'll raise it.
Sketch out a plan - we used SketchUp, but drawing on a napkin would work just as well. Basically you want a flat bottom, two risers on either side and a top. While you might be tempted to skip the bottom, it adds structural stability and prevents the whole thing from sliding around. A flat plywood bottom is also preferable to 2x4 bracing as it makes it much easier to slide the storage bins in and out.
Things to consider:
- size of the bed (we fit a double mattress with room on all sides)
- how you will fit in the storage bins (we made sure the openings were wide enough to utilize the most space possible)
- best use of lumber - you'll want to minimize the number of cuts and scrap