You need a RJ45 -> DB9 (serial port) cable. You connect it to the serial port of your computer. Then use HyperTerminal (on windows). Default port settings are:
baud: 9600
data: 8
parity: none
stop: 1
flow: none
Hit Enter after setting up HyperTerminal. That will get you into the command line.
>enable
Password: your password
Switch# show run to see your existing config
Switch# conf t
Switch(config)#
Switch(config)#interface fastethernet 0/11 say port# 11
Switch(config)#switchport access vlan 100 say vlan# 100
Switch(config)#end
Switch# wr to write permanently
Switch#show run to see changed config
