We get weight by eating extra calories and incorrect amount of macronutrients. There are two ways by which we can lose weight.

You know
1 gram of protein = 4 calories
1 gram of carbohydrates = 4 calories
1 gram of fat = 9 calories
1 pound of fat = 454 gram
So 1 pound of fat = 9*454 = 4086 calories

Note: Our body fat contains around 3500 calories, as 10% of it is water.
So in order to lose a pound of fat (4086) in 2 weeks, we need to decrease calories consumption by 290 per day as 4096/14=290(approx)

15 minute of good exercise will help you in losing around 100 calories. So in order to lose 1 pound of fat in two weeks, we need to exercise for around 45 minutes (290 calories) if we do not want to make any changing in our eating habit. So just take care of the amount of calories in the food you take. The best idea for losing weight will be by cutting down the junk food with exercising. So greatest way to lose weight is a mixture of diet and exercise as exercise builds muscles, and bigger muscles burn more fat.

First of all it is important to understand that it took 9 months to gain weight.
So that weight cannot be lost in few days. So it will take some time to lose that weight. It is not a great idea to lose more than 2 lbs in a week.

Women normally need minimum of 1,200 calories per day to remain healthy. To lose one pound per week, cut out around 500 calories from your intake and do regular exercises.

Try eating plenty of high-fiber fruits & vegetables as well as whole grains. Eat healthy foods. Avoid oily snack Eat more fruits, vegetables, grains, pastas and beans and avoid red meat and salads laden with dressing. Try to build some outdoor activity into your day. In some way walk with your baby every day and try to get a jogging stroller added to your wish list. Drink plenty of water. Avoid soda, cool drink and juice. Some foods are they were truly empty calories.