In the "When opened in a browser" list of options there is no "Launch a form".
To fudge this:
Create a blank navigator, call it launch ( not lunch unless you are hungry) .
Give the form you want to launch the alias or name "$$NavigatorTemplate for launch".
Set the "When opened in a browser" list of options in the launch tab of the database properties to "Open designated navigator in its own window"
Open the database in the browser with the .nsf eg: http://adfos.com/world-cup.nsf
Alternatively set to launch as a page and then add javscript in the page to launch the form.
See:http://www.notesninjas.com/A555F9/nn.nsf/ByAlias/WebFw
NB: This will not work with a view and a view template, you will receive a entry not found in index.