Help with a coop roof

I have stupid question. My run was broken into by an something I'm sure was furry and some damage was done. I always shut the coop and barrel lock the door and windows so the chicken were unharmed. To keep them safe I built a run inside my fenced in backyard where the dogs are so no animals will be able to get to them again. Now for the problem. While my wife and I were moving the coop to the new location with a hand truck (VERY heavy and hard to handle) we tipped it over and damaged the roof. I have it all set up now but it is not going to be water tight. Of course they are calling for rain for the next three days. I went to tractor supply and picked up a 6X8 tarp to cover the 4X6 roof with. How can I attach it so that wind will not blow it off? I have it draped over the roof tonight but will need to secure it tomorrow. I have a 2 inch gap all around the roof to wall area to allow for ventilation and don't want that blocked. I know this should be simple but I am tired and out of Ideas, please help.

 

Thanks, I should have done that. I just rolled it under itself and staple gunned it to the sides. Hopefully I can put a real roof on soon. I would like to use metal put it costs so much.