How to link F4801 WO# to supplemental DB Narrative desc of 254 chars?

Created a SDB code and attached a NAR Data class and DataType as DD desc of Job desc Data mode to N. Now how do we add the desc of 254 chars of Job plan desc and how do we link the WO# from F4801 to this 254 Char desc. which tables does it reflect and how do you view it. Please advise, I did this before however cannot remember now... thanks