Hi Mia, and welcome to the forum. I've been building these for others, so maybe I might give you some guidance.
First, you need to know what parameters you need, and how to get there. Those being Light, Water, Air.
I recommend using lattice on the sides, because while it offers shelter, it also allows a lot of air movement.
The top, you need to decide what you are growing, and what media you are growing. The easiest in south Florida is growing on mounts, whether it be cattleyas, phalenopsis, dendrobiums, or oncidiums. With mounts, you can get by with just shade clth on top, and not worry too much about excessive heat in the summer.
I grow mostly catts in pots, so we have corrugated plastic roof with shade cloth and sprinklers. Ideally with a covered roof, you would be better with a roof at least 9' high, if not higher.
While the best structure is all metal, it is not the most sightly to have in one's back yard. I build structures using pressure treated wood.
Here is a link to some of my work....
Some pics from work...
I need to update this as I'm finished with the second half of the main orchid house..