Cover any holes in the bottom of the flower pots with cardboard or newspapers. Mix the cement mix according to the package directions. One large bag will fill two flower containers.
Insert a landscaping timber into a flower pot and pour the concrete around the pole. Work on a level surface and brace the timber with a 2-by-4 wood section on either side of the post so it remains straight. Allow the concrete to harden, and remove the 2-by-4's. Repeat the process with the other three posts and flower pots.
Lay the flower pots on their side and drill a starter hole for the eye-hooks, 3 inches from the top of the landscaping timbers. Screw the eye-hooks into the timbers. Stand the flower pots in the desired location with the eye-hooks facing outward from the center of the four pots.
Starting from the inside, run the rope through the ringed hole closest to the corner of the tarp, then through the eye-hook on the timber and back out through the first hole on the adjacent side of the starter hole. Tie the rope in a knot on the inside of the landscaping timber. The rope will go through the tarp, through the eye-hook and back through the tarp. Repeat this process with the other three landscaping timbers.
Adjust the flower pots to keep the tarp taut so a gust of wind does not billow up the tarp. Stabilize the shade structure, for long-term use, by burying the flower pots halfway into the ground or running a guy-wire from the timbers to the ground.