To get started with "Spaces" you need to enable it because, most likely, it's disabled by default. Before we get into that, though, I have to warn you that it's a bit of a mind shift because instead of a 1:1 relationship between your monitor (the physical object connected to your computer) and the screen (the graphical representation of the information shown on the monitor). That can get a bit weird because you will be able to have applications running just fine, with all their windows open and functional, yet not be able to see anything on your actual monitor.

Sound weird? Yeah, it does take a bit of getting used to, but remember it's just like how your TV receives all the channels at once but is only showing on the monitor the image sequence from the channel you're "tuned in" to (unless you have picture in picture, but that's exactly how that works: the monitor displays two screens of data simultaneously).

Let's get started, though!

First step: enable Spaces in the first place. Go to Apple --> System Preferences...

Click on "Exposé & Spaces", then make sure you've clicked on the "Spaces" tab along the top of that window:

Along the top - and highlighted in this screen capture - is "Enable Spaces". Check that.

Now you'll want to determine how many virtual screens you want to work with. I have six by default, though lately I have found that four are sufficient for what I like to keep open and running. You might start with two just to get the hang of it. Notice also that you can create a grid or a long strip of virtual screens. Probably the long strip is easier to start with, but you'll see later that the Mac gives you a visual reminder of what space your in based on whether you have a grid or strip anyway.

Close the System Preference and you've got Spaces running. Nice.

Now, to get to the sort of super-view where you can see all your Spaces, all your virtual screens, at once, press Function+F8 at the same time. Your current window moves "back" and all the other windows show up, in miniature:

You can easily move app windows from one Spaces virtual screen to another by just clicking and dragging. Here I'm moving my Chromium (Chrome) web browser from space #2 back to space #1:

I typically have four or five apps running at the same time and like to have each live within its own Spaces virtual screen, as you can see in these two screen shots. Saves a lot of screen clutter (especially if you have the discipline to avoid having files and app icons on your Desktop too).

You can also specify which Space your individual apps should launch within, a feature I find super useful in terms of starting out with the organization I prefer. Do this back on the System Preferences pane:

No surprise, you can see that Mail is assigned to Space 1, Chromium and Firefox to Space 2 and GraphicConverter to Space 3.

Want to add an app? Launch it, then click on the "+" on the lower left:

Now it's on the list so you can assign it a specific Space or, often more useful...

Assign it to be visible in all Spaces you're using. That's how I have iTunes set up, for example, so that whatever I'm doing its little mini-window is visible on the lower left corner.

To navigate from Space to Space easily, don't use Function+F8, instead use Control-arrow. Want to move one virtual screen "left"? Use Control-<-. Try it! As you go, you'll see that Spaces gives you a helpful visual cue about what virtual Space you're in for a second or two:

In this instance I'm in Space #6, which actually doesn't have any apps assigned at the current moment.

Why is this useful? I find that having just one app's windows on screen helps me concentrate and avoid distractions and -- SQUIRREL! -- side tracking. Further, if you're in the middle of a game or some social networking goofiness, it lets you mentally put it aside while you're trying to be productive (or vice versa!)

Spaces might not be a winner for you, but it's a must-have capability for me on any Mac I use, and I can't imagine working on my systems without it.