It is necessary to specify the name of the SMTP server and the port number (usually it's 25). The SSL checkbox enables SSL communication, which may be needed by some SMTP servers (a typical example is Gmail’s SMTP server). In case a user authentication is required, select 'Authentication required' and specify Username and Password.
These parameters are the ones used in your e-mail client software, therefore all you’ll need to do is “copy” them from a working e-mail account.
To make sure the SMTP server is reachable just click on the Test connection button.