This is Gibbs 3.2 formerly located at http://ccmbweb.ccv.brown.edu/gibbs/gibbs.html
Docs are coming. :-) In the mean time, clone the repo, unzip src.zip, cd to src directory, and run: make -f make.linux to create a new binary. Test it by running: ../bin/Gibbs.linux ../data/crp.fa 16 20 -n -E 2