We use your profile information (gender, age, height/weight, activity level) combined with your desired calorie deficit percentage to calculate your calorie goal.
You probably calculated a calorie goal when you first signed up and went through the Getting Started Wizard.
If you didn't, go to Settings > Getting Started and follow the instructions.
If you'd like to recalculate your calorie goal, you'll need to change at least one of the factors used in the calculation.
To change profile info (gender, age, height/weight, activity level), select Settings from the main (left) navigation menu, then select the My Profile tab and make any desired changes.
To change your desired calorie deficit percentage, select the Macros tab from within that same Settings area, and select a new deficit percentage, which will automatically generate a weight loss goal and a calorie goal.
When you're finished changing your weekly weight goal, scroll down and select Apply My Macros.
If you do plan to enter and track calories, please also be sure that you've enabled calorie tracking.