Changing Header size on a single page

Hello,

I created two websites http://www.ares500.com (main site) and http://www.ares-500.com (an additional website) I would like to create my welcome page on http://www.ares500.com to be that shown on wwww.ares-500.com but in order to do so I need to edit the coding. How can I change it so the welcome page can look exactly like that shown in http://www.ares-500.com Please advice. Thank you.