To create a new formula, look in the Field Explorer window and right-click on the Formulas node. Then select New and give it a name.This opens the Formula Workshop window. You can drag fields from the top window into the edit window below. This automatically enters the field name for you so that you have the correct syntax. It might look something lke:

{TableName.TotalProcessedField}*3600/{TableName.TimeTakenField};

Save your changes (checking for errors) and then we you go back into design mode you can drag and drop this formula onto your report to print it.

I have complete coverage of how to write formulas and use the Formula Workshop in Chapters 5-7 of my Encyclopedia book. You can find out more about my books at Amazon.com or reading the Crystal Reports eBooks online.