First of all you require a Master Server in your environment. You would download the NetBackup Server software package for the OS on the Master Server from fileconnect. So we cannot answer which option you download until you know what platform you have chosen.
You do not install NetBackup into the ESX Server as this negates the whole idea for off-hosting the backups and not impacting your ESX Server resources. You can install the NetBackup client software into VM and back it up from the master server (this will slightly impact the ESX Server). Or you need to backup the VM's from a proxy server - off-hosting (minimal impact to ESX and VM)
I suggest you do some reading or further investigation. Do some searches in the forum for VCB.
This the function of VCB snapshotting from the VMware side.
I recommend you also read the white paper for NetBackup for VMware.
http://www.symantec.com/connect/articles/veritas-netbackup-65-vmware-3x-best-practices
Instead of NetBackup there is also Backup-Exec which allows backups of VM's at the snapshot level.