Connection/setup problem

I went through the steps to setup it i.e. unplug the cable router, plug the one end of cord to it and then power the router back up and then plugged other end to the wireless router. Then connected the computer to the wireless router in port 1 and then restarted the computer which it said to do in the guide after trying to see if the computer saw the connection which it didn't.

It didn't for alot of times and but one time it worked and the computer could go on the internet and then i put the router address in the internet browser and the dialog came up with the password and the user login, its was a pre-used network in the house, so there was a password and i couldn't get it. So i resetted it and the wlan light went out and following those steps i said before, can't get back to the dialog.

Thanks, if you tried to help