To create a group of IP addresses, navigate to 'Services' at a project level. Under 'Services' select 'Security'. If you have already created IP address groups you will need to click 'Manage Security'. From here click 'Create an IP Addresses Group'.
Provide a name to your group and the list of IP adresses you want to group and click 'Add'. After creation, you will either be able to edit or remove the group you have just created.