In association with identification information for identifying a representative of a community site, personal information about the representative and theme information are registered in a basic information database, while in association with identification information for identifying a member, member information about the member is registered in a member information database. Commodity information about commodities to be provided to the community site is registered in a commodity database in association with the theme information. The central apparatus extracts the optimal commodity information from the commodity database based on the theme information registered in the basic information database and then transmits the extracted commodity information to a terminal device.