When you compile a rookery with Rheo, each idea that you declare will produce its own standalone page. When you link to an idea using a hyperlink, by default it will link to that idea’s standalone page. (To link to the page in which the idea was actually declared, see #hyperlink.)
The standalone page will be minted at ideas/<idea-name>.html, where <idea-name> is the name you give explicitly or the one that is implicitly generated. The ideas directory is configurable through the prefix setting (see the site-config reference).