Joomla 2.5. Fix a bug and install template ready to edit content

I am new in Joomla and webs. I got a domain-hosting and I did istalled Joomla 2.5. I am triyng to use a corporate template for Joomla 2.5 that I bought from JoomlaMan. I upload the template and when I go and see the site appears...
Fatal error: Call to a member function Header() on a non-object in /www/sites/886/c73/www.mydomain.com/web/joomla/templates/jm_corporate/index.php on line 26.

I need someone to fix this and leave the template ready for me to edit the content content online.

Thanks,