dsl airport problems

[bobscliff]

i'm at someone else's house and they have a dsl modem. i know nothing about dsl, as i have cable. i've connected their modem to a router and connected it back to the computer, and i've also plugged my airport into a router because we have two laptops. the problem is, one of the laptops is getting internet access and one is not. the firewalls are all off, i've tried resetting the hardware, but nothing seems to work. i''ve set it up here before without problems, only this time. i need help!