If you need to invoice other people that aren't members of your club, you can do this via club contacts.
Click the "Add Contact" button to add one.
Complete the form then click the "Add Contact" button.
Invoicing Contacts
To invoice a contact, click on their name, then click on the "Invoices" tab"
Click the "Create Invoice" button.
Complete the form then click the "Create Invoice For Contact" button.