The following instructions are quoted from the Classic Accessories:
On each side, along the bottom of the cover, there
are three hooked straps for securing your cover to
the bottom of your golf car. Hook the straps under
your car at the front corner, back corner and in the
middle by the door, then adjust the tension with
the buckle on each strap.
You can find the full set of instructions for this cover by going to http://www.classicaccessories.com/product_files/07cG59_002_FairwayDlx4SidedGolfCarEnclosureInstr.pdf.