Develop a commercial invoice report

Hi,

Currently, I am working in AX 2012; I need to develop a “commercial invoice” report similar to Performa packing slip report on the Sales order form. I need a separate action button commercial invoice on next to the Performa packing slip button. It is only used for customs’ valuation. Once clicked it will generate the commercial invoice report for a recent items "packing slip"ed. Just need to understand how to do this and where to start.

Thank you in advance…