Using Template HTML Editor, you can edit online selected template's index.php file. That way you can make changes to the way the template looks. In order to be able to save your changes, the index.php file must be writable. Its status is displayed next to the file name, above the editor. Be sure that is set to Writable.
Checking the "Make unwriteable after saving" option, will change file's permissions in order to make it unwritable.
Save: Click the "Save" icon to save changes.
Cancel: If you want to discard changes click "Cancel" icon.
Help: This Help Screen.