Please enter a node name/URL portion using a-z, 0-9, _, and - characters only.
They match the forum/style exactly - the same elements are used to build the page.
You can see that here: http://xenforo.com/community/pages/example-page/
Some more examples are here - click on the node navigation menu on the left to see more: http://www.cliptheapex.com/community/pages/2011-race-hub/
They exist within the forum structure - you will notice the Forums tab is highlighted when viewing a Page.