The bare-bones installation of Odoo simply provides you with a limited messaging system. To manage your Odoo implementation, you must begin by planning the modules with which you will work first. Odoo allows you to install just what you need now, and then install additional Odoo modules as you better define your requirements. It can be valuable to take this approach when you are considering how you will implement Odoo for your own business.
Don't try and install all the modules and get everything running all at once. Instead, break down the implementation into smaller phases.