Hi 4J1a,
Are you booting from the SD card? The SD card is mandatory for Wi-Fi, since the driver is not available from the SPI image. Take a look at the Intel® Galileo Getting Started section 11 for instructions on how to set the SD card.
If you are booting from the SD card, the wireless card driver might not be installed. Which wireless card model are you using?
Regards,
Intel_Jesus