A DSL router connects your DSL modem to a network hub so your computers can share the Internet connection. The function that the router provides is to translate the internal IP addresses and combine the packets from those addresses into one stream to go to the Internet and properly route incoming packets back to the workstation that requested them.
Some routers also provide a firewall to prevent hacking of your internal network from someone out on the Internet.
The router itself shares only the Internet connection but you can easily share files or printers among the computers on the internal network just by enabling sharing.
Your network will look something like this:
--DSL---DSL router-----hub---- workstation1 |----- workstation2
|----- printer1
|----- printer2
Hope this helps!
paul