how to take excle file backup automatically and put password on excel file

Automatic Backup (.XLK) when File is Saved (#auto)

Setting up for automatic backup of a file.  (on a single file basis, not global)

• Save the file
• Save As (F12 key), then on the Save As Dialog menus: Tools --> General Options, check “Always create backup copy”.  Answer “Yes” when prompted to replace the old document.  Your new document is identical except that the new one saves a backup each time you save the file.

Now, as to the backups: they are always one save behind the original document.  Excel backups have the original name and the suffix .xlk (with a displayed filetype of “Microsoft Excel Backup File”), and will appear in the same folder as the original.  With the Excel backup you can use Autosave and backup simultaneously. 

What is the difference between bridged, NAT and host-only networking? Which should I use?

A virtual machine in VMware Server, Workstation and Player can have virtual network cards that are "bridged", "NAT" or "host-only".
In Linux, a network of each type is created when running vmware-config.pl. In Windows, they are automatically created. If you didn't create them the first time vmware-config.pl was run, you can re-run it.

Comparison of the network types
Type	Bridged	NAT (Network Address Translation)				Host-only
Description	The VM appears as if it was a physical host on the network.	The VM hides behind the IP address of the VMware host. Other VMs in the same NAT network can access it directly.				The VM can only access the VMware host and other VMs in the same host-only network
IP address	The VM requires it's own IP address from the network it is supposed to  belong to.	The VM can have any private IP configured on the VMware host.
Accessibility from network	Same as a physical host	Hides behind NAT, so port forwarding on the VMware host required if external access required				Not accessible from external network unless routed via another VM with access to both external network and the same host-only network
Use cases	An always-on server hosted on VMware, or a virtual router or firewall	VMs intended for testing, or cases when the amount of IP addresses in the external network is limited.				VMs intended for testing with no need to access the network, or VMs which will be protected by a firewall in another VM.
Other	Known to have problems with some wireless chipsets especially with Linux, also with Windows Vista.	NAT is really a host-only network with a default gateway (on the VMware host) that routes and NATs.