First download PuTTY (download and run "putty.exe"). After installation is complete, open PuTTY and enter
under Host Name (or IP Address) (see #1 in screenshot below).
Note: If you are not a Computer Science student you can replace csil.cs.ucsb.edu with linux.engr.ucsb.edu instead.
Then make sure you have selected the SSH bubble and click Open (see #2 in screenshot below) at the bottom. If a pop-up mentions a "PuTTY Security Alert", click Yes. It will then prompt you for your engineering username and then for your password. After you provide both you should be successfuly logged in.
Note: Other remote access tools for Windows can be found in the FAQ under How can I access my UNIX account from Windows?.