Are you Dynamic?

Hi guys, sorry for being such a newbie, I got a question about updating a website’s content Dynamically (just learned how to spell it, sorry its that bad) I wonder if anyone knows any easy-to-add scripts (PHP,XML,FLASH) so that:

-There is a simple online form, and my client can login, type in the content for a page, and that text will appear on the site. The site will be in HTML but can also be in FLASH.
-Essential that it supports á ã ç etc as the page is in PORTUGUESE.
-If Images also can be added even better!

Many thanks!