How do you reduce the mac desktop?
If you mean you want more "space" on the desktop, say, have two
windows side by side, then you'll have to RAISE the resolution of
the screen monitor. The higher the number, (1280x960 is larger then
800x600), the smaller the icons and the more "room" is available on
the desktop.
If the icons get too small you can "Right Click" on the desktop,
select "Show View Options" and then set the size of the icons.
Your video card and monitor dictate how large you can go. If you
have a 'tower" type Mac (MP, Power Mac, etc) you can upgrade to a
newer more powerful video card and/or monitor. If you have a laptop
then your stuck with the video card you have. You can hook up an
external monitor but your still limited to the video card.
If you have a 28" monitor capable of 2500x1200 and your video
card can only support 1024x960 it still won't have any more space
to work with. You'll just have one very large window.
If you just want smaller icons to see more of the existing
desktop you can "Right Click" on the desktop, select "Show View
Options" and then set the size of the icons. You can also set the
size of the Icons in a folder the same way too.