did you download the *.gz or the *.bz2?
if you have a different version, edit as appropriate
tar zxvf apollon-0.8.7.tar.gz
tar xjvf apollon-0.8.7.tar.bz2
either one will create a directory called apollon-0.8.7
./configure && make && make install
if it blows up, it'll tell you why - maybe
if it works, just type the program name and off you go.