see how to change the view you're working in.
If you hold down the middle mouse button you can
rotate your view (if you don't have a 3 buttons mouse, you
have to use alt + left button).
The combination ctrl + middle button allows you to
zoom in or out.
Shift + middle button allows you to pan.
Here are the keyboard shortcuts to change the view :
1 : Front
7 : Top
3 : Side
0 : Camera
+,- : Zoom
/ : Selected objects
2,4,6,8 : Turn around your view
5 : Perspective view
Ctrl-x : Back to the default scene
it ! You can now navigate in your scene.
3 : Manipulating objects