Draw a line from the bottom center grommet to the 2nd to the top grommet, another line from the bottom center grommet to the 2nd to the top grommet on the other side, and then draw a line to a 2nd to the top to the other 2nd to the top. Look at the previous step and it will show you where to cut also. [The grommet in the boxes]. It will be excaltly the same as the model.
Next thing you do is cut the lines with the scissors. Make sure that you cut on the outside of the grommets instead of the inside ans that you leave some of the tarp around the grommets.