[Orgmode] org-learn question

[Piter_]

Hi all.
Can somebody tell me more detailed instruction about how to make "learning data" for org-learn mode?

>5. Your "learning data" is kept in a special property called :LEARN_DATA:. Do  not modify this, as it controls how the algorithm reschedules after future   repetitions, and based on past quality responses.

Thanks.
Petro.