Edit the file /etc/munin/munin.conf, adding records for each client
Records are of the form:
[descriptive_name] address clientname.your.domain use_node_name yes
'descriptive_name' is the name which will appear on the pages for the client
'clientname.your.domain' is the IP or domain name of the client
'use_name_name yes' tells the server to use all the available plugins (each type of statistic has a plugin) for the client