If so, it should contain:
(I personally think that these are common sense, but people do seem to be getting confused about it.)
It should also link to FAQ 25 on changing usernames.
If you have two accounts on LiveJournal, log out of one. You can log out with the logout button in the top righthand corner.
Depending on your log in options, you may be able to log out by closing your browser. The FAQ referenced below gives more information on log-in options.
You can also post comments or entries from one account, while still logged in to another account. Simply enter your other username and password.
When posting, there is an option to post as another user. (http://www.livejournal.com/update.bml?altlogin=1)
When commenting, there is also an option to post as another user; you may have to click the "More Options" button to see it. Do not click the "Log-in?" checkbox for the secondary account.