Sparkpeople and Weight Watchers

I want to lose 5 pounds by 10-31-3010 so I went to SparkPeople.com and signed up.   The site calculated I should be eating 1800 to 2010 calories per day. That is approximately 36  to 40 weight watchers  points. I must also burn 1080 calories per week which is do able.  This eating when hungry, calories and points seems like a math equation that finally makes since.   The exercise is only 18 minutes per day which is do able. Man I feel all over the place.  The SparkPeople.com site says I need to burn 360 today to meet my goal so my exercise of choice is Stationary Bicycling: vigorous for 15 minutes and I would have burned 370 calories