At the center of the team's activites is ‘The Model’. A model is simply a representation of the way something behaves, a map of cause and effect linkages. In this case the model represents the way the simulted business envronment behaves in response to your decision and those of your competitors.
While teams are free to build their own models if they choose, many find it easiest begin with the Excel templates provided with the software. There are four workbooks: for market forecasting, production planning, capital budgeting and financing activities. These are not comprehensive or definitive. You will certainly have to elaborate on the basic skeleton to get to something useful.
Indeed, Cindy Nimrud, a member of one of last year's teams, developed a simple single-page sales forecastng spreadsheet. I think it is easier to understand, once you comprehend its structure, than the template that comes with the simulation.
This is a link to her Excel workbook (Nimrud - Submission form.xlsx)