Am new to Agile and need some help in identifies user stories for a given feature. The feature is "application should generate a delimiter space file which the fields given in the field specification document. First file will be a full feed, followed by incremental feed on weekly basis. each file has a file naming format"

for this requirement, how do i come up with user stories? I want to split user stories in a way that each story is either 3 or 5 storypoints which is a testable entry.

plz help me with high level user stories that i should come up with?

Thanks.