An administration tree is a set of files and directories which form the configuration of a linux station. A configuration tree has a name. The name is used to create a sub-directory in
/etc/linuxconf/admtrees
Each tree is a replication of the layout in /etc, /var and friends. So for example, for a tree named "mynet", you have files like
/etc/linuxconf/admtrees/mynet/etc/group
/etc/linuxconf/admtrees/mynet/etc/passwd
/etc/linuxconf/admtrees/mynet/etc/hosts
/etc/linuxconf/admtrees/mynet/etc/ppp/pap-secrets
.
.
Linuxconf has the ability to operate in this "sub" environment in the same way it operates with the standard configuration files found on your station. The content of those files is the same, format wise, as the ones in /etc and friends. As such you can use linuxconf or any other tool to update them (a text editor, a script).
The administration tree has no operational role on your machine. Linuxconf access this tree only when