Need help with linking connections

Hi, I recently bought a Linksys WRT160N Access Point but I want other devices to connect to the internet through it. I don't have DSL internet but I access the internet through a 3G data card which connects the computer to the internet through the USB port. So I wanted to know if someone could help me by telling me how do I setup a wireless internet connection, in other words when I connect the 3G data card to the internet then I want the access point to provide access to the internet to wireless devices such as PSP, cellphone, etc....

I'm using a Hauwei E220 which is a 3G data card, but apparently I cannot find the share-connection feature as yet. I only use the interface of the access point to change setting, so how do I possible link up the two together?