Before you install this script in your cgi-bin directory, change the following lines as necessary. This line is correct for most of you. Create a directory where you will keep your logs. You can put this any where you would like.
Every server is bound to be different.
Substitute yourdomain for the name of your domain on the server. This will point to a directory that you will need to create. Your path may also be different. Check the path your ftp-client is using, it will be the one you want. If you are on a virtual server, you won't see your domain name in the path.