How to modify what comes out of Description fieldon the LedgerTransStatement Report

Hi All I have an issue i am trying to solve, All transactions that come through the Purchase Order are returning "Vendor invoice" on the description column of the LedgerTransStatement report. I want it to output either the Product name[PurchLine.ItemName()] or the Procurement category [Ref_EcoResCategory_ProcurementCategory.Name] on the Description column.How do i achieve this.