Hi Carl,
It all depends on which switch you are having , it should be a layer 3 switch. For example if you have 3550 switch then you just need to enable "ip routing" and the create logical interfaces for vlans like interface vlan 2 and so on and assign an ip address to them and once you connect the devices to these vlans like workstation these logical interfaces which are layer 3 interfaces will come up and it will start routing between different vlans.
Also if you want any physical port to work as layer 3 port you can give a command "no switchport" and assign an ip address to it.
You can run routing protocols on layer 3 switches depending upon the switches like 3550 SMI version only supports rip and igrp but 3550 EMI version supports all routing protocol like rip, eigrp , ospf and BGP as well.
Remember switches like 2950,1900,2900xl and 3500xl are layer 2 switches and cannot be used as layer 3 switches.
HTH
Ankur
