To set up a task reminder for a specific user in SharePoint:

1. Navigate to the list or library where the content is stored.
2. Select the item you would like to assign to the user.
3. Choose the Assign To dropdown.
4. Type the user’s name or email address to choose the user.
5. View or select the Reminder dropdown and select a required time and date.
6. Choose OK to apply the reminder for the task.