can't logon to airport

my husband turned on the computer & clicked on safari before the modem was fired up. This brought up the airport brought up the username & password. He typed in the info & it rejected it. We tried several times & now we have been kicked out & having to use the ethernet line to connect to the internet. How/what do we need to do to get back on the internet using the Airport w/a new name & password?

do we need to start all over again?

Each time I go in to system preferences, & click on network, it brings up Ethernet connected/Airport not connected. When I click on the Airport on the left side of screen, the connection says Airport is on, network name is Stephen1. When I click on Assist Me, it brings up Diagnostics (which says there is nothing wrong) & Assistant (which makes feel like i'm running in circles trying to answer the name, passwords info taking me to set up network). Since we can't remember our password because we rarely had this problem (& didn't write it down anywhere) we're assuming we need to set up a new user. But how do we do this?