Download and installation.

First, download the appropriate program file from the web page. There are separate versions for different platforms (at present, Windows, Sun and Linux). The Windows file is an executable installation file. Double click on the icon to start the installation. You will be guided through the installation. Run the program by double clicking on the structure icon. On a Unix system, put the file into an appropriate working directory. Then, unzip the file (``gzip -dc $<$filename$>$ $\mid$ tar xvf - ''), where $<$filename$>$ is the name of the downloaded file. Run the program by typing ``./structure'' in the appropriate directory. People on a Unix system can also install the program into a standard directory for programs, e.g., /usr/local/structure. You then need to set an environment variable e.g., $STRUCTURE\_PATH$ to the structure package installation directory. For bash users, the syntax is: STRUCTURE_PATH="/usr/local/structure'' export $STRUCTURE_PATH in the .profile file; for csh/tcsh users put setenv STRUCTURE_PATH "/usr/local/structure'' in .tcshrc or .cshrc. You can then run the program by typing $STRUCTURE_PATH/structure