To fix your most immediate problem, you can use the Selection tool, and over an empty area of the canvas, click-drag the mouse past the edge of the screen. That will force the canvas to be panned. ("panning" is what you're talking about, in Inkscape language) Or you can drag an object over there.
I would suggest reading about it in the manual, except that panning controls were changed with the current version 0.91, and the manual has not been updated to 0.91 yet. But I think some of the controls still work. Here's a quick way to get an idea about it. Help menu > Key and Mouse Reference. Click that and it will open up a webpage with all the key and mouse controls. Find the section on panning, and experiment!
As bartovan suggested, zooming is a way to bring the whole page into view. But you should understand a few things about zooming. If you have a large page size, such as the default size A4, and you put the canvas at 100% zoom, you can't see all the page borders. 100% zoom is the true image size. (You can see the zoom amount in the bottom, right corner of the window.)
When you first open a new blank document in Inkscape, the page size is A4, and the canvas is at 35% zoom. (This is one of my pet peeves about Inkscape!) The only reason I can think of why it's like that, is so that you can see the whole page on the screen.
However, if you draw your image at 35% zoom, and if you save it that way, then when you look at your image somewhere else besides Inkscape (in a picture viewer or uploaded to the internet) it will be Huge!
Actually, there's no real reason you need to see the page borders at all, until the very end of finishing your drawing. There's an option (Document Properties > Page tab at the bottom) to turn off the border.
I usually work without the border showing. Then when I'm finished drawing, I select my whole image, and then go to that same page in Document Properties, to the Custom Size section, and click Resize Page to Content. And then click Resize Page to Drawing or Selection. That fits the page border perfectly to the drawing. And you can see in that section in Doc Prop where you can set margins, if you need blank space between your drawing and the border.
