connect Yun into (DHCP enable) ethernet LAN;-
download putty:
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
setup putty:
http://drupal.math.arizona.edu/support/account/remoteshell/putty.html
keep port number:22
computername:arduino.local
if "arduino.local" does not work, follow this link to find out Yun ip address and use ip address.
http://forum.arduino.cc/index.php?topic=188101.msg1583686#msg1583686
username: root
password: arduino