config.php is not writeable.

CHMOD config.php, errors.txt and the subdirectory /paintings to 777 and reload this page.

* CHMOD (abbreviated from change mode) means to change permissions/attributes of a file or a directory on Linux and Unix based systems. This can be done with any FTP program. On Windows servers, look at the options of your hosting control panel or you may need to ask your hosting provider to make these files and folders writeable.