Cmdlets are usually implemented around resource operations. The four basic operations are CREATE, READ, UPDATE and DELETE. This set of operations is known as CRUD. Most of the cmdlets support CRUD which are respectively cmdlets that start with the New/Get/Set/Remove cmdlet verbs but they also may have additional operations.
Step 1: Retrieve a object by running a Get command
You can READ objects by using Get-OvfConfiguration cmdlet. See example below:
$datastore = Get-Datastore -Name 'MyDatastore'
$ovfPath = "myOvfTemplate.ovf"
$ovfConfig = Get-OvfConfiguration -Ovf $ovfPath
$ovfConfig.NetworkMapping.VM_Network.Value = 'VM Network'
Import-VApp -Name 'myVApp' -Source $ovfPath -OvfConfiguration $ovfConfig -VMHost $vmHost -Datastore $datastore