First, if you have a livejournal account, you will need to create a Chesspark account using your livejournal username.
See the following urls :
I used this one, so the username I put in the form field was firstname.lastname@example.org
Note the '@livejournal.com' , you will need to add this when creating and logging into the account.
Now here is the only part where it may get confusing. You have to enter a Chesspark password. This can and should be different from your livejournal password. It is used to access the Chesspark website and not the live game server. This will be changed soon and support for openid is in the works. So fill in your Chesspark password, but remember to use your livejournal password on the next part.
Next we want to play some games. To get to the live game server you can use the web or download a client.
Going to the play url or starting up the Chesspark application you will be presented with a login screen.
Here you will enter your full livejournal username and password. ( NOTE: not your Chesspark password from above).
So, I enter email@example.com and my livejournal password and I am off! Playing Chesspark with my livejournal account!
So, how does this work? Well, Chesspark is XMPP based and can communicate with other XMPP chat servers. Livejournal has XMPP chat and when you log in with a Chesspark client you are actually logging into livejournal.com. After that you can communicate via livejournal to Chesspark and do anything you like as if you were on the Chesspark server.
I hope this helps and have fun!