Craft Edge

I am new to Inkscape, so I was wondering if anyone out there can tell me if there is a tutorial which tells about Nodes, what they are for and how to manipulate them. Also what effect they have on a picture you are trying to cut. Thanks in advance for any help you can give me.

The best one I can think of is Dan99's on how to remove something from an image.
http://dan99.blogspot.com/2008/12/video ... f-svg.html
Looking at the outline mode (View>Display mode>outline) is the best way to see how node changes effect the path, which is what is ultimately cut.