If you're new to java, here's some starters.
PlanetGenesis requires an installed java 1.4.x runtime
If you want to use the 3D previews you will need Java3D. Try the following links...
Windows and SPARC Solaris
For more other OS's or if the others links are dead try.
http://www.j3d.org/download.html for more information.
pG runs for definate on Mac OSX and Windows, I've not tried it on any of the *nix's
but I have had reports that it runs on x86 linux.
To run it, first unzip the zip file. Mac OSX users can then double click on the jar file,
that may work on windows too, or you can drop down to a command shell, cd to the directory
with the jar file and type
java -jar planetGenesis.jar
Nearly forgot...on Win2000 there's a bug in Direct Draw with some graphic drivers.
If you get regular blue screens or reboots when trying pG...
a) swear at Microsoft for putting graphics stuff in the kernal
b) use the command line and try
java -Dsun.java2d.noddraw=true -jar planetGenesis.jara) will get you no where but is good for your karma,
planetGenesis has a simple GUI that looks like a flow chart.
For more detail on what the icons mean click on the image map below.
The tooltips look like something like this depending on your OS.