If you already have existing switches/hubs that are not able to use fiber modules, then you could purchase media converters. Transition Networks is the brand that we used. www.transition.com
If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem. Also please exercise your best judgment when posting in the forums--revealing personal information such as your e-mail address, telephone number, and address is not recommended.
Network 3 building via fiber uplink
all 3 building are 500 ft apart in a line