Time for some backups

[Roger Beever]

Hi.
I have been reading the rsync man pages but am not sure what is the
right commands to do what I require.
I just want to back put the home directory and sub directories from one
machine to another.
For easy of explanation a.net is the machine I want to backup and
a1.a.net is the machine I want to put the backup on.
They are both on my small LAN so no extra security would be needed.
Which command do I need please.
The backup directories do not exist yet but I believe that does not
matter please correct me if I'm wrong.
Thanks in  advance.
Regards Roger