untar it, move it somewhere (mine's in /usr/local/thunderbird, my mom's is in /opt/thunderbird) then make a symlink from the thunderbird executable (mine: /usr/local/thunderbird/thunderbird) to somewhere in your path...like /usr/local/bin. e.g:
Code:
ln -s /usr/local/thunderbird/thunderbird /usr/local/bin/thunderbird
then each user need only type 'thunderbird' to run it.