Let me try to give a better explaining.

this procedure will do the you create a new dashboard in your horizon aplication (new tab beside the 'Administrator' and 'Project' tabs).

you'll find where is all the directories of dashboards (directories named 'Admim', 'Project' ... in my computer is /home/user/Docs/horizon/openstack_dashboards/dashboards)

there, you'll choose a dashboard that you want modify, and duplicated it.

you will change the name of the directory duplicated and you'll add this dashboard in the INSTALLED_APPS and HORINZON_CONFIG.

Look, the link that you'll acess the dashboard will be the same, but a new dashboard there will appears.

Now, to add you new dashboard in the aplication, you'll put the directory adress in the INSTALLED_APPS and the name of the directory in HORIZON_CONFIG.

in INSTALLED_APPS, you will (obviously ; ) ) install your new dashboard and in HORIZON_CONFIG, you will just "say " to horizon, that have your dashboard

I have helped.

INSTALLED_APPS = (
'openstack_dashboard',
'django.contrib.contenttypes',
'django.contrib.auth',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.humanize',
'compressor',
'horizon',
'openstack_dashboard.dashboards.project',
'openstack_dashboard.dashboards.admin',
'openstack_dashboard.dashboards.settings',
'openstack_auth',
'openstack_dashboard.dashboards.nameofyournewdashboard',
 )

HORIZON_CONFIG = {
'dashboards': ('project', 'admin', 'yournewdashboard', 'settings',),