A Weigh-In is necessary for work and power calculations because it will give us your height and weight (the numbers we use to calculate power output.) If your power output is saying 0, it's probably because you don't have a logged weigh-in.
To log a new Weigh-In use the "+" button in the footer menu. Then click on "Weigh In" from the available tiles.
You don't have any power output data because you haven't logged a Weigh-In or set your measurements. From the web, a Weigh-In can be logged via the "Log" button in the header. Click on "Weigh-In" from the drop-down menu.
Measurements are a little different. These can only be set via the web. These consist of your squat, shoulder, deadlift, and overhead heights for lifting exercises. Without this data we can estimate some of the work done, but you'll get better results once you post accurate measurements for each. We use a mathematical formula to determine the work done in each repetition for each exercise that you do. Go to your personal drop-down menu in the header and click on "edit prefs".
Then select a measurement unit and enter in the appropriate numbers for each of the categories.
Please keep in mind, since we don't have a formula for every exercise in the database (especially those added by individual gyms), your work output may differ from what is displayed.