|Then you need a Router (wired or wireless) and then a switch with enough ports on it to support the number of users. |
Wireless routers also have wired ports.
Routers have one port that is used for uplink. That is the port you use to connect to the switch.
Crossover cable is required between the modem and the router. That may be supplied with the Router.
This assumes you have a broadband connection with a modem. The Cable/DSL connects to the modem. The modem to the router. The router to the switch. Users can connect to either the router directly or to the switch. If all users are to be wired it is best to have them connect to the switch. The switch should be a 10/100MB or better. Some examples are at the link below.
If others have ideas or opinions feel free to jump in here.