I admit I haven't got all caught up with my lessons here, so I'm sorry if this has been covered. Do you upload graphics in different dimensions or just one, like 4 x 5 ratio, and let FB crop and alter as it wishes for various placements? I know some are saying you can just use one size and make sure everything is in a center safe zone. Others say that FB appreciates us creating various sizes for various placements. Thanks in advance.