Welcome to NGA
@Ashley2023
Did you watch all of the videos? The materials needed are listed in the 2nd one, "shopping for materials." (However, the GH in the videos is 14x20 so you may need to adjust the amount of materials if you make one that is a different size.)
Best of luck with your project - we have a forum here devoted to greenhouses and you would be welcome to to post there with your progress!
https://garden.org/forums/view...