I can't turn on the window

I’d like to ask you how to turn on preview window in Blender 2.68a. I make the film and I can’t see the preview. (see image from Blender 2.49)

I see nothing in the VSE. It will be black till you load a image or vid and have the frame selector on the time line on the image strip.
Go to Add …

I have added the movie and there is still nothing

Now ya tossed me a loop your in 2.6 now. I do not know for sure. but you can try to drag the window bigger by dragging it down. Do not know why but often it will change from strip to preview and back to strip window when it is small again.

Thank you very much! I did what you said and now is ok