Facebook .net database application

I would like to create a small facebook application to track mini database entries for users. The user would be reminded regularly to enter a value when they login to facebook. When they add the value, a calculated result will be returned based on the previous values they have entered. This result will be placed in their feed. For example, they would originally enter a beginning body weight, date of birth, and goal weight, once a week, when they login they will be asked their current weight. A percentage of goal weight loss will then be added to their feed. I will provide the formulas for calculating results and database structure.