How to schedule the Schedule Apex ?Wer it will store???

you can schedule the schedule apex by

RemindOpptyOwners reminder = new RemindOpptyOwners();
// Seconds Minutes Hours Day_of_month Month Day_of_week optional_year
String sch = '20 30 8 10 2 ?';
String jobID = System.schedule('Remind Opp Owners', sch, reminder);

Or You can schedule it directly by clicking on schedule apex