Tap Reminders.

Tap the new reminder icon.
Key in the required text.

You have a number of other options after you've created a reminder.
Choose one of the following options:
Add alarm, go to 3a.
Set priority, go to 3b.
Mark reminder as complete, go to 3c.
View completed reminders, go to 3d.

Tap the required reminder.

Tap the indicator next to Remind Me On a Day to turn on the function.

Tap the date.

Drag the wheels to set the date and time.

Tap Done.

Tap the required reminder.

Tap Show More....

Tap Priority.

Tap None or the required priority.

Tap Done to save.

Tap Done.

Tap the box next to the reminder.

When the box next to the reminder is ticked (V), it's marked as complete.

Tap Completed.

Tap the required reminder to see it.

Tap the Home key to return to standby mode.