In this matrix, check the boxes for sites that are linked together. The default is to have the site itself also display the linking, but if you do not desire this (if you have a different hover effect you want to see, for example) unckeck the boxes that link the site to itself. You have the option here of select the sites that link to this site, or selecting the sites that this site links to (incoming or outgoing). This will determine the kind of relationship you want to display.