Windows 2000 LAN / WAN

Ok I need some help here. I have a Linksys Cable/ DSL router. I am trying use FTP to share some files. Now I have 2 IP Addresses A LAN and WAN. When I setup a FTP server (Usually download free ones off Cnet), it says the host is 192.168.1.102 which is my LAN IP not WAN. How could people access my files on my PC through the internet? I use Cable Internet Access. Is there an easer way to do this?