OZJournals is a small, simple and basic blogging software that is coded in PHP (Hypertext Preprocessor).
The data is stored in flat files, thus it does not rely on and will not be requiring databases such as MySQL or Postgre.
If you prefer to create your own theme(s), you only have to copy a few necessary scripts from the header.php, footer.php and style.css files.
After creating a theme, choose a name other than "default" for the folder in which you place the header.php, footer.php and style.css files. You can also include other files such as pictures and flash presentations to make your theme more presentable.
You can always edit the CSS from the Admin Panel. It is recommendable that you keep a backup of your files (themes, etc.) somewhere outside the main directory.