Kim, here's how I have my two greenhouses anchored. The photos are of the one I built last Nov but the one I put together in 2014 is anchored the same. I used 3' T-Posts and drove them in as far as I could which usually came to about 18-20" in the soil I have here. I used 3 posts per side one on each end and one in the middle. Then two cables per post run through the hole in the post with the cable clamp. I can't remember exactly what size cable I used or clamps but you can use what you want as long as it fits through the holes on the T-Posts.
