jacowacko,
From the sound of your post, you've confused 2 different things: Static websites and Dynamic websites.
Using a CMS produces dynamic websites, where the "pages" are built "on the fly." You can still use a WYSIWYG editor, however you need to modify other things such as:
Themes and/or Styles
Nodes or whatever the particular CMS uses for "pieces" of the website.
If you edit the actual "page" per se, you're headed for a mess, and frankly, the CMS will not function correctly at all. At best, you'll get a static page that probably does not have everything where it's supposed to be.
What you COULD be referring to is something like
FCKEditor or
CKEditor, where you can allow "members" to edit certain portions of a "site" such as blog posts, forum posts, etc.
Let us know if that's the case, and then give a little more detail as to the specifics of your issue/problem (so, maybe give us a walk through type example of what is not happening that should be.