Okay, this should get you started, at least. Convert the JPG to a BMP, drop ham6.bmp into your OOTP6/Graphics folder, and then go into the game, Edit Ballpark, and Import Park and point it to hammona.txt and you should have something decent.
(I thought the photo said "Hammona" not "Hammons", sorry.
)
You'll have to do the dimensions, park effects, and weather yourself.
Hope this helps...