You can send an email to a friend to encourage them to join LiveJournal at the Invite a Friend
This page generates a personalized link to the Create New Journal page. Your journal will be automatically added as a friend and the page will list some of your active communities with the option to join. When your friend accepts your invitation, we will email you their new username, so you can friend them.
You can also search for friends that are already using LiveJournal using the Find Your Friends