The tarball XThermoSpider.tgz contains the binary executable XThermoSpider. To extract the file you can use the following command at the command prompt:

tar xzvf XThermoSpider.tgz

You need to put the extracted file in an appropriate place on your system, for example /usr/local.  You should also create a shortcut on the desktop to the application.  Refer to your distribution's help guides for information on how to do this.