sudo apt-get update  
sudo apt-get upgrade  
sudo echo "deb http://nightly.openerp.com/9.0/nightly/deb/ ./" >> /etc/apt/sources.list
sudo apt-get update
sudo apt-get install odoo
sudo service odoo start
You can now access Odoo from: http://your_vps_ip_address:8069
Example: http://162.243.69.108:8069