GL Journal

What is GL journal. How to create GL journal and how to post GL journal. Where can view the posting result. What is the workflow. Can anyone explain to me…?

-Urgent-

Below are some useful links to begin with,

http://technet.microsoft.com/EN-US/library/aa551623.aspx

http://technet.microsoft.com/en-us/library/gg231032.aspx

thanks for the link.
i am creating GL journal based on information from invoice.
i dont know how to find main account for this.

can you help me on this?

i know what is the main account and the dimension value. But i dont know how to customize this in the code.