To email you junior contacts navigate to the 'Contacts' module on the left-hand side of your admin page.
You can filter for juniors on the 'Junior' column and place a tick next to the juniors you wish to email, or place a tick in the top tick box next to the Unique ID field to select all.
Then select the envelope icon:
The recipients will be the email addresses of the main contacts assigned to the junior contact record.
If no recipient appears then check if there is a parent / guardian assigned to the account.
Select anywhere along the row of the contact you would like to check. Scroll down and you will see the 'Parent/Guardians'.
When emailing junior contacts from within a membership package, you need to ensure that you change the selection from 'Members' to 'Main Contacts'.