Eating more if you have excercised

When you set your activity level and weight loss goals (1 lb/week, for example), it gives you a calorie goal that will allow you to lose that much each week without exercising... So when you exercise, you are allowed to eat those calories back, which MFP encourages, and you will still lose that 1 pound a week as long as you don't exceed your calories.

They're not saying if you go for a walk and burn 200 calories, go out and splurge and eat 1000 calories in ice cream and such...

I personally don't generally eat back my calories, but it's a personal preference.

The calorie goal that MFP has given you already includes your calorie deficit.
If you exercise, you need to log and eat those calories, otherwise your deficit gets too large and becomes unsafe. It isn't personal preference, that is how this website is designed.

There are quite a few stickied threads around the forum that answer questions just like this for new people, maybe you should give them a read?

This.
I ate back my exercise calories and it worked out just fine.

I vary it. Sometimes I eat over, sometimes under. I am most cautious if I can only work out a little or take a rest day. Like today, I ran 7 miles and am allowed another 963 calories if I want. We'll see how I feel. I may go for a bike ride later too, if the rain cuts back. I could easily add another 900 in a 15-20 mile ride.