Stuck setting up wireless modem.

Hello. We're trying to acquire a wi-fi signal by upgrading our internet connection from a wired to a wireless connection, but having some problems. We purchased a Motorola 2247-N8 modem and followed the instructions on the installation disc. But after choosing the ethernet option, it required a pppoe username and password. When choosing the wireless option, it requires a wireless adapter. I'm not familar with a pppoe username and password or wireless adapters. Could someone please explain a possible solution for us? Thanks.