[LUNA] icon question

[Michael W. Hall]

I have a question about icons.  I have an icon and I need to create two
more versions of it.  I need a medium and small version.  The one I have
will be the large version.  

Question is how can I use GIMP to reduce the size of the icon for the
medium and small versions?  I cannot draw worth a crap, so I was hoping
that I could shrink the icon and save it as different sizes.  The other
icons we have the large, medium, and small icons are 32x32.  How do I
change the actual image size?

Sorry if my terminology is not correct, I am not a graphics person.
These are for a windows app that I work on at my job.  I thought I could
edit the icon on my Ubuntu personal laptop with GIMP easier.

Thanks,
Michael