Usually these kind of things are best done from the command line
put the example below in a new file under /etc/cron.daily/
and chmod +x filename , for it to be executable so that it can be automatically run
on on a daily basis.
lftp -e 'put /home/path/yourfile.tar; bye' -u user,password ftp.theserver.com
the -e command is to allow you to enter a series of commands.
The commands to be run are declared within the ' ' signs,
in this example two commands are run in succession each command is separated by the ; sign. The first command uploads a file, the second command disconnects from the ftp server once the upload is complete.
If one would want to add an additional command, for example to browse to a another folder simply add the change directory command , "cd folder1/folder2;" in our example the new command would look like this:
lftp -e 'cd folder1/folder2; put /home/path/yourfile.tar; bye' -u user,password ftp.theserver.com
lftp can take script files as input allowing you to create separate files with commands for it to execute when using the -f option if you feel like having the commands run my lftp separated into a specific file.
if you want to see what commands are available this can be help
for generic ftp commands. Commands specific for lftp can be found in the lftp man page