I'm afraid I didn't write down what I was doing as I was doing it, so it is a bit difficult to remember at this point. This will be a very rough tutorial.
This is how I made it:
This fun geometric fabric came from U-Fab in Richmond, Virginia; I purchased 4 yards.
Next, I measured all the sections of the ottoman. Essentially, the slipcover would be a bunch of rectangles sewn together with piping in between. Then I created a sketch with the measurements.
I worked in sections. First I sewed the cording to the top rectangle. Then I added the side rectangles to the top. Then, I added cording to the side pieces, then I added the bottom pieces.
I usually pinned the pieces together while the fabric was on the ottoman. Sometimes I found it easier to do this with the fabric inside-out.
Finally, I took the legs off the bottom, stapled the fabric to the bottom and then put the legs back on. Then I stuffed the extra fabric between the top and bottom ottoman cushions.
Voila! A slipcovered ottoman--not perfect, but it will do!