|what kind and how many poles do i need to build a tent 7lenght 7height.|
|Here are detailed instructions on making an inexpensive hoophouse style greenhouse using plastic sheeting. You can adjust the length to suit your needs.
Here are excellent discussions of home greenhouses including the A frame style with different types of covering.
Note that the plastic sheeting needs to have support every two to three feet and that the structure must be strong enough to withstand winds. I hope this helps you with your planning.