Although you can activate Spaces or use the Spaces menu to navigate between the spaces you're working with, the faster and easier method of getting around is to use keyboard shortcuts. Spaces allows for three sets of shortcuts.
The first is the shortcut to activate Spaces. This is useful if you don't want the Spaces icon cluttering your Dock. As I said earlier, the default key for this is F8, but you can select any of the function keys using the "To activate Spaces" pop-up menu in the bottom section of the Spaces preferences. A second pop-up menu allows you to assign a mouse button to be used to activate Spaces (obviously, this requires a two-button mouse).
The second set of shortcuts is for switching between spaces using the arrow keys. The pop-up menu for this option ("To switch between spaces") lets you select a modifier key that switches between spaces using the arrow keys (the default key is the Control key, but you can also choose the Option and Command/Apple keys). This is handy if you have only a few spaces and know where they are in relation to each other.
The final set of shortcuts works much like the second, except that it allows you to switch directly to a space by typing its number. Again, you can select the modifier key if you don't want to use the Control key, which is the default. This is helpful if you have more than a few spaces and want a quick way to move between spaces that aren't next to each other.