how to add fields in zreport Output

Hello ZSAP Guru's

My client req is to add fields in Zreport output. what is the best possible way to do it....i dont know where to start with as the environment is all custom...i am not a technical person but i know if working in ZSAP environment one should know.all the technical aspects.

Please guide me on this path to achieve this milestone.

all the fields are standard fields.

Requesting the Guru's to show me the direction so i start my analysis

thanks a lot in Advance