crystal report dynamic field

hi, i found this off the crystal decisions website and i'm still puzzled by how it works. i've attached the project, plz review it and explain to me how the database' fields correspond to the formulas

my questions are:-

• how to assign the formula fields to the appropriate table fields? where is it done in the report designer?
• wat does the codes below mean?
  
  Code:

  ---

  'set the Formulas collection to the current report's formula collection
crFormulas = crReport.DataDefinition.FormulaFields

'set the 5 formula fields in the order they appear on the report.
crFormulaTextField1 = crFormulas.Item(0)
crFormulaTextField2 = crFormulas.Item(1)
crFormulaTextField3 = crFormulas.Item(2)
crFormulaDBField1 = crFormulas.Item(3)
crformulaDBField2 = crFormulas.Item(4)
crFormulaGroup1 = crFormulas.Item(5)

  ---

plz help


thx,
gildan2020