no edit:
The browser you decide to use, because it don't matter what one. (firefox, internet explorer, netscape, aol, opera)
They used to enter your physical router (that thing plugged into your modem, or the modem itself on the floor under your desk) when the routers address is typed into the address bar, your not actually on the internet at that address.
there are generic login and passwords that you can mix match them till they work. they listed somewhere on help pages or found on a google search.
usually:
login: admin
password: admin
or both of them left blank and entered. there are more default ones to, i cant think of them. also your parents might know all this, and set a new password on it themselves.
once logged into the modem/router your able to find the settings to forward port ranges.