If you go to http://www.fitbit.com/activities you will be able to track your activities so that the fitbit knows what you were doing at a certain time. This is also handy if you are travelling by vehicle as long journeys can add to steps/floors!
As for tracking elliptical, you can scroll to the bottom of the page to 'log activities'. If you start to type 'elliptical' the site will bring up a choice of 'medium' 'low' or 'high' resistance. You can pick which resistance you used, and what time you used the elliptical at, and how long for. 
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