Openstack network queries

Hi Please help me understand openstack networking. My understanding: - We have three type of virtual network in neutron. 1.flat 2. Vlan 3. Vxlan/gre Based on the above type wat are the different ways we can create private and public network. Private network only for internal ip of instance. Public network will create submit and use as floating ip. We can either assign public up network from network provider or can use ip address which has internet. Please give example for each case. Regards, Dhan.