The Search Form is simply a form with a "key" entry and "Submit" button:

<form action="${SiteURL}search.htm">
<input class=field type=text name=key size=12>
<input class=button type=submit value=Search>
</form>

The search.htm (a virtual page) will take the input "key" and search all editable text to display a list of pages.  Only pages accessible via to the session will be shown.  For example, a search without a login will not show pages of Member access level.