(a) Create document root to store mrtg graphs/html pages:
# mkdir -p /var/www/html/mymrtg/
(b) Run any one of the following cfgmaker command to create mrtg configuration file:
#cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg.cfg public@localhost

Note : To query only specific interfaces, use :
#cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg.cfg –ifref=ip public@localhost

Note that there is –-ifref=ip additional syntax. So far, this is only for interface that has IP address and up(???) 07 Nov 2009 Hendrik Suantio

OR (make sure your FQDN resolves, in following example i'm using rh9.test.com which is my router FQDN address)
# cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg1.cfg public@rh9.test.com
(c) Create default index page for your MRTG configuration:
# indexmaker --output=/var/www/html/mymrtg/index.html /etc/mrtg/mymrtg.cfg
(d) Copy all tiny png files to your mrtg path:
# cp -av /var/www/html/mrtg/*.png /var/www/html/mymrtg/
Step # 6 First test run of mrtg
(a) Run mrtg command from command line with your configuration file:
# mrtg /etc/mrtg/mymrtg.cfg