Unix
cd ~/course/hh3st modlunit k3.mod
MSWin
Open a "command prompt" window, then
cd c:\course\hh3st c:\nrn62\bin\modlunit k3.modAn alternative is to start modlunit by double clicking on it, then use "Choose directory" to navigate to the directory that contains k3.mod (or use "Recent directories" if you have already been there), and finally double click on k3.mod.