to have more than one search parameter, you need to use the advanced recordset dialog box
in the tutorial i linked to, see the "Build an advanced results page" section
to show a message if the search returns no results, use the Show region behavior.
type the message, then select it, in the server behaviors table, click the plus button and select Show region -> Show If recordset is empty, select the recordset for your page.
to return no results for an empty search, set the default values for the parameters in the recordset to -1
This is all fairly basic dreamweaver functionality.
I recommend getting a dreamweaver book like the Foundation PHP Series by David Powers