You can have a portlet page call another page in a portlet application. So, page 1 can have a link that makes page 2 appear. But you can't have a portlet provide a like that makes itself disappear, and makes another reappear.
You're still in a Servlet/JSP mentality. Stop thinking of portlets as though they were JSPs or Servlets. You need to bend your mind into the portlet world.
Sounds like you might be trying to do a wizard like application. Why not just use the JSF or Struts portlet? It will allow you to easily provide a wizard like experience to a user, all within a single portlet.
Keep asking these questions though. Let me help you think like a portlet developer.