Check the Hardware Compatibility List for the exact model number of wireless NIC you have. Just saying it is Linksys and it doesn't work is not much help, so no one can help you.
It would also help if you told us what you have already tried.
To get the wireless card to work you need to have the correct driver, it needs to be compiled, then loaded into your kernel. Then you need to configure the wireless card including any router security settings.