Using the ASCE 7-95,
use the formula
qz=.00256*Kz*Kzt*V^2*I
Kz=.9 for open terrain (use 1.08 if your on the edge of a large body of water (1 mi accross))
Kzt=1.0 (unless you are on top of a large hill, then =2.0)
V=80 mph (this is given by you, check your local building code official because this will very important and may vary if your by the coast)
I=1.0
I get qz=14.7 psf
Then use formula
F=qz*G*Cf*Af
G=.85
Cf = 1.3 (for a 30% sloped roof or greater, conservative for slopes < 30%)
Af=total area divided by number of posts
I get 16.2 psf *12 ft * 12 ft/4 posts = 583 lb/post
This does not take into account loads from overturning due to wind of the entire structure.
Get yourself a Simpson ABU 44, and use the bolt option.
Make sure you provide a large enough footing to hold down 583 lb of uplift (at least 2 ft x 2ft x 1ft)
HTH