First, you need to make sure that you have your VMKernel network interface configured correctly so that it can connect to your iSCSI target. Second, you need to go to Configuration -> Storage Adapters, where you will see one of the adapters is the iSCSI initiator. Select that and do properties, enable the adapter, and then Rescan the HBA and you should be able to connect to your iSCSI volume, assuming you've configured security correctly on the NetApp box.
