To automatically scale your VMs in the same virtual datacenter:

In your virtual datacenters, create and configure networks
1. To optionally use VPNs between VDCs (see Connect virtual networks with VPNaaS), use networks with different addresses, e.g. the default network and a custom network set as the default, see Manage Networks
Create and configure your VMs. See Manage Virtual Machines
1. Enable metrics. See VM monitoring and metrics.
Define scaling groups for VMs. The base VM can be deployed or undeployed. See Manage Scaling Groups
While you are creating the scaling group, select the Create autoscaling action option
1. After you save the scaling group, select the Metric(s) that will drive the scaling
2. To check and further configure the scaling, click Show more
3. Optionally add more metrics

The platform will automatically create scaling actions that are driven by alarms and alerts on your metrics.