To setup your Data Center, Storage, Networks and Clusters connect to
https://CLUSTER.YOUR_DOMAIN/ovirt-engine/ and login with admin and the credentials you supplied during installation.
Following this guide setup is pretty straightforward.
Add ISO Image
#ssh to your ovirt engine ovirt-iso-uploader -i YOUR_ISO_DOMAIN upload YOUR_IMAGE.iso --insecure #(if you are using a self signed certificate)