I can really only suggest reading the user manual for it. They're usually fairly helpful in these circumstances. The Connection Details page here details exactly what you need to put for all the details (username/password/etc).
You should note that Windows XP usually treats xDSL connections as Dial-Up connections unless you have a router and as such you still need to dial a phone number. It doesn't matter what you put as the phone number, the modem will ignore it. IIRC the default for my old USB modem was something like 38,0 but, again, the instruction manual should tell you more.