It depends on how you installed. In Ubuntu you can go to <ip>/horizon or<hostname>/horizon.

http://<server_ip>/dashboard

if u use RDO in a multinode enviroment have a check if there are some problem to

vi /etc/openstack-dashboard/local_settings allowed host=

comment to let everyone use the dashboard end restart httpd

I used to get the dashboard by accessing http://ip/dashboard after installation. How did you install Openstack?

Suggest you start with a DevStack Build, Its easier to install and to get working locally.

http://devstack.org/

Access your controller IP from any browser on port 8000. Better yet, RTFM.