Users with existing LiveJournal accounts can generate a limited number of "invite codes" to allow another person to create a free LiveJournal account (http://www.livejournal.com/support/faqbrowse.bml?faqid=104).
To generate any invite codes that may be available to you, visit the "Invite a Friend" page (http://www.livejournal.com/invite/) and click "Generate more codes". Any invite codes available to you will then be generated.
To view the invite codes that you have generated, return to the "Invite a Friend" page (http://www.livejournal.com/invite/). You may need to refresh the page to see your new codes.
You can use the invite code yourself, or send it to someone else.
To send an invite code to someone else, you can copy the URL of the [use] link next to the invite code and send it to your friend using some form of communication program. The URL will look like this:
http://www.livejournal.com/create.bml?code=aefh3aaakgse (note: this code is invalid)
You can also write the invite code down and give it to your friend. In this case, your friend should then visit http://www.livejournal.com/create.bml, and enter the invite code manually.
Invite codes are not re-usable. Even if the person's account is deleted or suspended, or simply isn't used, you cannot get the invite code back. Think carefully before you give away a code.
For information on how many invite codes you are eligible to generate, see http://www.livejournal.com/support/faqbrowse.bml?faqid=103.