At HiOS you globally create and delete areas and then assign interfaces to them.
By default, i.e. if you haven't configured otherwise, the area ID 0.0.0.0 (the backbone area) is used.
At HiOS devices you have to disable OSPF at the concerned interface and then enabling OSPF again with the correct area ID. OPSF can be configured by CLI.
Following an example with new area ID 1.1.1.1 at interface 1/2:
<login>
<pass>
enable
configure
ip ospf area 1.1.1.1 add
ip ospf area 2.2.2.2 add
interface 1/2
ip ospf area-id 1.1.1.1
ip ospf area-id 2.2.2.2

This script first assigns area 1.1.1.1 to port 1/2 and then - as a change - area 2.2.2.2. An interface can belong to one area only.
Please note that with current firmware releases (at least till 7.0.0) an area can also be implicitely created by adding an interface to a not yet configured area. This is for "compatibility" with Classic router scripts, but deprecated.
Please make sure that all interfaces within one area have the same hello time and dead interval configured.