This will be reset during the performance of the program, and could be set to 2 now, if you wish. Unless you have some reason to alter this number, leave it at the default value. If you know that the data do not suffer from this, then you can set the value to some much lower number. A safe bet is 20. For simulated data, then 2 will do.
Group is a number used by the kd-tree search routine.
We recommend you fool with this only if you are uncontrollably curious and know what a kd-tree routine is. Otherwise, take the default and march on. At this point all your numerical options are set. To do this you go back to the main menu and invoke Plot as usual. Might as well leave this at 1.