instantiate Sparta canvas?

''I am an abstract class and should not be instantiated. However, the best way to create an instance of sparta canvas is to send extent: message.''

!! Example:

Create an empty canvas of size 400@250:

[[[language=smalltalk

canvas := SpartaCanvas extent: 400@250.

]]]

So, how do instantiate and display a Sparta canvas?

Where can I find good documentation about Sparta?

Thanks.

David