1. Upload 'guestbookdb.php' on your server using BlueFTP.
2. Change the permissions of 'guestbookdb.php' to 755 otherwise you won't be able to write data.
You can use the FTP Manager add-on (BlueFTP) to upload and change permissions of the 'guestbookdb.php' file.
a) Login to the FTP server of your website using the BlueFTP.
b) Browse to the folder where you've published the guestbook.
c) Upload 'guestbookdb.php'
d) Select the file and use Properties to set the permissions to 755
You only have to do this once.