First go to router setting by using the router ip like "192.168.1.1" or "192.168.1.0" u can use any browser. then it will ask u username and password u can find those info at the back of the router, mostly by default it is "admin" for both username and password, after u logged in goto Setup->wireless setup ->wireless security, you'll find the keyword "pre-shared key" then enter your password in the text box then press apply. THATS IT!