How can I hook my old 1998 mac with only an ethernet port and no usb port up to my wifi internet?

All other computers in the house either have wifi or wifi adapters. I ordered a male ethernet to female usb adapter to try to connect a wifi adapter to it. Will that work or will it also need power since it's not a usb port? Also, can I split one wireless adapter between two computers or would they each have to have one?