howcanilinkanlogouttoanlogoutpage

You can modify templates/global.vm and replace the URL to use when clicking on the logout link.

Namely look for:

#set($logouturl = $xwiki.getURL("XWiki.XWikiLogout","logout", "xredirect=$util.encodeURI($logredir)"))
      <a class="glink" href="$!logouturl" id="headerlogout">$!msg.get("logout")</a>#sep()

And replace xredirect value with the page you want, for example to redirect to Space.Page:

#set($logouturl = $xwiki.getURL("XWiki.XWikiLogout","logout", "xredirect=$xwiki.getURL('Space.Page')"))