Lay Out Design

I am trying to design a lay out for an invoice that has about 2 inch wide and 2 1/2 inch long. I have tried everything I know of the system from changing the parameters in the document properties/Paper format in the lay out designer to trying to change the lay out fields manually. I have also tried to look for information on the lay out designer but there is not much around.

Do you guys have any leads or recommendations for my situation??

Regards!!!