I have At&t internet. I know its possible to also connect through wireless to another computer. HELP!?

Well ok- i need answers ASAP! My husband is in Japan and this is really the only way that i can talk to him. I bought the AT&T. I know you can set up a network of computers through the wireless. Normally my computer picks up the connections but i have never actually had to connect through the wirseless. Its not even showing up though. My mothers computer is wired to the box (modem or router i dunno what it is)... I dunn oif it is just to far from it or what!?! I need help!