new at this

ok this may have been posted many times but i had no time to go through it since i am in a hurry.Just wanted to know that i have a usb modem.Now i want to create a wireless connection with my notebook.I have a wireless buffalo airstation turbo g.So what i did was connect the the airstation to my ethernet card which was in my pc.now i can access the notebook over the network but cannot give internet access to it .secondly the notebook cannot access the pc.What can be the reason.Help would be appreciated.is there anyway that i can internet connection with the current stuff that i have.