BackupMulticraft allows you to make backups of your server (these can be automated using scheduled tasks). From this page you can create server backups by clicking the start button. This page also provides you with connection details for accessing the server via FTP. Typically FTP details will be in the following format:
Host: Servers IP address
Username: Multicraft username with a . and and a number
Password: Your Multicraft login password
FileZilla (http://www.filezilla.org) is a free cross platform FTP client that has been tested to work with the Multicraft FTP server.
Once you have created a backup of your server a copy will be kept on the server with the name "world.zip" (where "world" will be the name of your current world). As you create multiple backups the old backups will be renamed to "world1.zip", "world2.zip" etc.
Your hosting provider will have set a maximum number of backups allowed, once this is reached any new backups will overwrite the oldest file.
It is recommended to take regular backups of your server. Please note that for most hosting providers backups only include world files and do not include plugins or configuration files.