How do I create and modify an ExpressRoute circuit?

Refer to:

https://docs.microsoft.com/en-us/azure/expressroute/expressroute-howto-circuit-portal-resource-manager

Selecting AARNet as the provider...

Once the above is completed, you will need to copy the “Service Key” and provide that to the assigned AARNet engineer. This allows us to identify ylour circuit within our portal and begin the provisioning process.