You need to configure your router WAN settings as your internet service provider.
If your ISP gives you static ip then configure it as static.
If ISP gives user name and password to connect inteernet then configure router as pppoe.
Connect your router to computer with ethernet cable then you can access it with following default link.
http://192.168.0.1
or
http://192.168.1.1
If you are not able to access it with above ip then check your computers ip address gateway ip is your router ip try with it.
Then it ask for user name and password.
Type user as "admin" and password as "admin" or "password" or blank.
Then you can see configuration page of router.
.
Click on wireless settings enable wireless then WEP Security then add WEP code .It is your password to connect wi fi.Then save settings and restart router.If you are able to see password in * or # then you need o add new password but if you are able to read it then note down it then you can connect with it.
If you are not able to access router with above ip and user password then press RESET button for 10 seconds it is in back side of router.
Then you can access it with above method.

Let me know if you need further assistance.
Thanks for using FixYa.