My b2evolution Version: Not Entered

Customizing the Write page in administration or other....

Man... I looked everywhere to find the css or php file to customize the Write page, and I searched the forums too...

So if I may ask for some help... I'd like to add a few lines of text, especially to the area on the right hand side of the Write page, under the Categories box where it says.
"Note: Cross posting among multiple blogs is currently disabled."
could you direct me to the file I can edit.

thanks group !
Rob