I am running a report that shows how much we have paid vs how much we have been re-imbursed by the company we are a dealer for. 

Here is the tricky part... 

I need to show a total at the bottom of how much we have spent, BUT, the data will need to be totalled in a really obscure way.... 

To shorten it right down I need a field that works like this 

There are 3 Fields : FIELD1, FIELD2, FIELD 3

FIELD3 CONTENT = IF ($Value of FIELD 2 = GreaterThan $0, then Display FIELD2) else (Display FIELD 1 Content)

So my question is : How do I create FIELD 3?

I hope this makes sense...