You can do like these:

1. modify dashboard.py This file is in this directory:/usr/share/openstack-dashboard/openstack_dashboard/dashboards/admin In this file,there is a class SystemPanels,you can add a item to its attribute panels like this: panels = ('overview', 'metering', 'hypervisors', 'aggregates', 'instances', 'volumes', 'flavors', 'images', 'networks', 'routers', 'info','alarms')
2. create alarms directory create a directory named alarms in /usr/share/openstack-dashboard/openstack_dashboard/dashboards/admin In alarms directory,there are at least 4 files: panel.py,urls.py,views.py,__init__.py and a directory templates You can make these files and diretory referring to other direcroties in admin,such as routers,info and so on. Each directory in admin is represent a option in the system panel.