Hi Victor,
Hm, there seems to be some basic understanding missing. First, if you need a JSP for your UI, a JSPDynPageComponent instead of an AbstractPortalComponent might make much more sense, just as the framework delivers primarily the eventhandling which otherwise you have to implement by yourself (of course this is possible, but not graceful at all). See for example Tutorial III: Building a JSP DynPage - Portal - SAP Library and around.
Then your concrete error comes from "<FORM name="helpForm" method="post" action="login.ChangePassw">". The "action" is translated into a call for a URL relative to the current URL, and it uses "login.ChangePassw" as value. This leads to the portal looking up an application "login" with the component "ChangePassw", which does not exist.
Then, you defined the ComponentType as servlet where in fact you wanted an AbstractPortalComponent, which is defined by not passing any parameter for the ComponentType (but the same holds for JSPDynPage or DynPage; just for native servlets and pure jsp's there is the possibility to leave the standard portal way).
I would urgently suggest to work through the Developers Guide (see link above), as it makes no sense to get this straight bit by bit here in the forum.
Hope it helps nevertheless
Best regards
Detlev