Make sure that you have the right to write in /templates/. If you don't have the right, you will need to change the directory privileges of /templates/ to something like 777, depending on your installation.

Overview

The link to the editor is located in the styles-menu. If you click it, a fork of the currently used template will be created, if that template is not itself a fork.

Renaming

You are able to rename the files in the template: Hover over the filename with the mousepointer for 2 seconds until the background gets coloured. Now, a click on the filename opens the editbox. Enter the new name and confirm with enter.

Shell_exec

When saving a php file, it is necessary to check for syntax-errors. Saving a syntax-error would result in an unusable blog, so it would be necessary to shell_exec() has been disabled for security reasons