Hi kpjj31,
Can you use window.open as suggested here? http://www.javascriptkit.com/javatutors/openclose.shtml
Are you looking for some value to be returned by seconddomain.com? If yes than you will have to set document.domain as shown here: http://jszen.blogspot.com/2005/03/cross-domain-security-woes.html
Regards,
Chinmay