i am a noob when it comes to networking myself.
i only joined this forum about 2 days ago aswell. this forum seems quite in-active.
so heres my 2 cents.
the "domain" could be referring to the DNS , which "should" be the address of your router.
usually something like 192.168.XXX.XXX , it should be available on the sticker on the router itself.
about your username , you should of been given a username when you first joined up with your internet service provider.
for example: firstname.lastname@example.org
you should of been prompted to create a password with it. you might have to ring up your internet provider if you need to recover it.
usually you type that username and password into the router settings itself.
so i am a little unsure about the "username" you are referring to.
all you should need to connect is the network name , security password.