I can talk pre and post.
I get up at 5 so I can finish eating at 5:30 and have an hour before I run. I run either either really hard and short (3 miles) or at moderate pace and long (10 miles). The meal is a pro complex shake, 100g of oats, and 20g of flax. That comes to 810 calories.
Post-workout, I have a suger-free replenisher drink with 50g of dextrose added, a whey shake, and then about an hour later 75g of oats. That's 743 calories.
You have to get a feeling for what is right for you, but unless you are doing cardio to loose weight, a good mix of carbs and fat plus some digestion time before hand is a pretty good idea. If you are trying to loose weight, a very light carb meal would be good.