The home screen on the N900 is called the desktop (just like on your actual desktop computer).

On the desktop there are a few shortcuts which are there by default - like links to the Ovi store etc and one of them is the video tutorial. Clickin on that will launch the tutorial video in the media player.

One of the things yo can do (and should do) is create your own shortcuts of contacts (people you call frequently) on the desktop as widgets.

Remember there are 4 screens on the desktop (in other words 4 desktops) - which you can arrange with categorized shortcuts. You access each screen by swiping the home screen from left to right.