To use the pretty graphs you have to first build/run the ltmtest from the root directory of the package.  
Todo this type 

make timing ; ltmtest

in the root.  It will run for a while [about ten minutes on most PCs] and produce a series of .log files in logs/.

After doing that run "gnuplot graphs.dem" to make the PNGs.  If you managed todo that all so far just open index.html to view
them all :-)

Have fun

Tom