First Timer!

Hello!
My name is Bea. This is my first time counting calories and being on a serious diet.
I am a former competitive swimmer, who swam all the way through college.
I have never needed to diet or watch what I eat, because I spent 3 - 4 hours a day swimming.
After graduation, I spent less time in the pool, and started a desk job, I have gained over 40 lbs!
I hate it. I can't even go up the stairs with out getting winded. I used to swim a mile in under 20 minutes!

I'd like to lose 65lbs by the end of the year, but my real goal is to be a size 8, instead of a 16/18.