An 8.5 by 11 inch piece of paper should be cut so that it is 5.875 (5 + 7/8) by 11 inches. There are two parts to the folding of this model. The first is tedious, and the second is difficult. In the first part, the paper is creased many times, and in the second it is contorted until it forms a spring.
The rectangles are folded row by row in groups of 6. Holding the paper with the long dimension going left to right and the grid folds appearing as valley folds to you, fold the leftmost column over the one adjacent to it. Make the diagonal fold on the uppermost rectangle (the upper right corner moves towards you and down). The second column's top rectangle can now be folded away from you using the first column's top as a guide. Fold the 3rd through 6th columns (as a unit) behind the second column, reversing the crease between columns 2 and 3. You can now repeat the folds you performed on columns 1 and 2, and then repeat the whole process one more time for columns 5 and 6. Repeat this whole business for all 12 rows. You are now done with the EASY part.
It is hard to describe how to perform the twisting. If you proceed slowly, it should be clear what you need to do (though maybe not how to do it). To get started, hold the paper with the short dimension running right to left, the diagonal creases appearing to you as valley folds, and the diagonal in the upper left corner running from northwest to southeast (turn the diagram 90 degrees to the right). Working from the left to the right, collapse the diagonal folds and the vertical folds to form a fanlike circle. The rest of the paper will form a cylinder below your hands. After you have fanned the circle, pry the former upper-left-corner part out until it lies on top of the circle. You are now at the second diagram of Fuse's instructions. Collapse and twist each section of the tube until you have a flattened spring (Fuse's 5th diagram). You can work the spring as indicated in her 6th and 7th figures.
Often, the spring doesn't work smoothly at first. You must soften it up a bit while in it's "unsprung" state, and perhaps do some detail work where one part of the spring slides inside another part. The spring should be stored in a compressed state so it is more willing to expand and contract for you. It wasn't until my 4th or 5th try that I was able to fold a good spring. Now it takes me about 30 minutes to make one if all goes well.