Kindy copy this steps in notepad and also copy the screen shot before u start doing it.
You can put up a wireless password manually b logging in to the router interface but you should be very careful because if you change any thing else it might be a messup your whole router so kindly do the following steps alone.
Step 1: Open the internet explorer
Step 2: Clear the address bar and just type the number alone which is 192.168.2.1
Step 3: You will get router screen as below
Step 4: In the left corner of the page under "Wireless" Security and select security mode as "64 bit WEP "
Step 5: Type any 2 numbers per box as u like and apply changes. Also make sure that you are gonna copy the password. If you want to connect any other computer in future you will need to have that password to connect.
Step 6: Under security in left side select "WPS or Wifi Protected Setup" and select WPS as disabled and apply changes. Dont worry it not related to security its just an option that has to be disabled if you enable the 64 bit WEP password.
Step 7: Then Connect wireless computer to the wireless network name and will ask for the password this time since password has been enabled. And ur router is gonna be a protected one and no one can hack it.
Step 8: In case if ur not able to connect to the network remove the preferred network and connect to it.
To remove preferred network
Start -->control pannel --> Network and Internet connection-->Network connection --> Right click on Wireless network connection icon --> Select 2nd tab Wireless network --> Remove preferred network one by one.
Windows Vista/ Windows 7
Start -->control pannel --> Network and Internet connection -->Network and sharing center --> In the left side select Manage Wireless network and remove preferred network one by one.
Check out the screen shot to enable security on the Router and to disabled WPS