It sounds like you want to create a table on the AS/400 — i series
This isn’t usually done in RPG – that’s a programming language.
There are two ways to create a table on this system
In SQL — from a prompt line on the green screen – STRSQL
Use SQL create table command. F4 is you want to be prompted for the command.
Older method – write a data descriptive script “DDS” and compile it.
Need to know which you are doing so we can hlep you more.