The Phylip Software was developed by Joe Felsenstein at the University of Washington. It is designed to take a multiple alignment and perform various phylogenetic analyses to show the evolutionary relationship between the different seqeunces.
This software is rather difficult to use. It is best used from within the GDE interface (SeqLab editor or GDE).
You need to give it a multiple alignment. The ClustalW software can save its output in Phylip format
Phylip On-Line Manual