If you read these instructions as a printout please go to http://help.nceas.ucsb.edu/Visitors to follow the links.
Ethernet: Plug in a cable, most computers will auto-configure the network setttings using dhcp.
Wireless (Wifi): Follow the instructions here: How to connect to the NCEAS wireless network ?
Sending email from the NCEAS network should work without any changes to your email client. However, some institutions will require the use of webmail or a VPN to send mail from a remote network.