How do I secure my network - D-Link Computers & Internet

1. • 1 Right-click on your network bar in the bottom right corner and click "Open Network and Sharing Center." You can also click "Start" and type "Network and Sharing Center" in the search box. Click on the Network Sharing center link in the search results list.
     
   • 2 Click "Manage wireless networks" on the left-hand pane.
     
   • 3 Highlight the network you wish to retrieve the WPA or WPA2 security key from; right-click it and select "Properties."
     
   • 4 Click the "Security" tab to see the security settings. The type of security will be listed along with the encryption type and security key. The security key will be hidden.
     
   • 5 Check the box labeled "Show Characters." The network security key will now be visible.
     

In your web browser address bar type "192.168.1.1"(without the quotes)
click the "Wireless" tab on the top
click the "Wireless Security" subtab
In the selection box select "WPA Personal"
Type your desired password in the " WPA Shared Key" field
Click "Save settings"

You will now have to enter your chosen password when you join your wifi network

Both are security protocol which enable the owner of an wireless network to limit the acces to that network and to protect the data that runs through that network.
WEP stands for WIRED EQUIVALENT PRIVACY and it' a security algorithm designed for wireless networks with the intention to provide a level of confidentiality close to the wired networks
WPA stands for Wi-Fi Protected Access and it's a security protocol designed to secure wireless networks
If your wireless device discovered a network that require such keys,that means that the owner of
that network secured his network,only people having acces are those who know the key.
If you have a Wi-Fi router and you forgot the key ,you have to acces the configuration page of the router ,go to wireless security page and reconfigure it, by changing the key.(get the manual of the router and follow the steps)

The name 'network security key' is itself self-explanatory. Every network has a security key and you will need this key to be a part of that network. Just as is the case of any other term that comes from the field of network engineering, there are a lot more details attached to this term, too. So, let us try to understand all the aspects related to network security key

An explanation as to why we need a wireless network security key is not even required. Still, if any one is skeptical about adding any complexity to their available wireless network, just think about it. Your wireless network range can be detected by any other computer with a wireless setup and that comes within the range of the network. So, without you knowing, it's very easy for any user to get connected to your wireless network and gain access to all the data that you intend to share only with those computers with which you have setup your wireless network. So, what is a wireless network security key and how is it useful in such situations?

Well, a network security key or passphrase is something like a password, which any user who wants to connect to your computer will require. But, I think that before we go into the details of figuring out, how to get network security key for wireless computer, we should take a look at the different methods of securing your wireless network

The MAC network card needs configuring with the router's security settings ie. SSID and encryption code etc, otherwise it cannot connect to the router wirelessly.

By setting up WPA2 encryption you are securing your wireless network from unauthorized access.
For details on how to further secure your wireless network, please click on this link and follow my instructions :-
http://www.fixya.com/support/r3559128-wireless_router_security

Wired Equivalent Privacy (WEP)
WEP is an older network security method that's still available to support older devices, but it's no longer recommended. When you enable WEP, you set up a network security key. This key encrypts the information that one computer sends to another computer across your network. However, WEP security is relatively easy to crack.

Do you want to secure the wireless network ?
For that you will need to access the router set up.
You said that you want to add a password. I don't understand that. Is your wireless network already secured ? Or you want to make it secured ?
If it is already secured then it must have the password to connect to the wireless network. You can use only 1 password for the network. You can not use 2 password for the wireless network.
If your network is not secured yet then you will need to make it secured and enable password protection on it.
Click Here to know more about how to make it secured

you will need to log in to your router.
in the wifi section select the wpa/psk security and use the serial number of the router as the security key.
you will then need to use this same number to access the router using wifi