failed to open stream Help!!!!!!!!!!

Hi
I have installed and customised a blog at http:/www.advancedthermal.com.au/Blog but when i embed it in to an exsisiting page on the site i get the following error.

“Warning: require(./wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in /home/content/74/7000374/html/Blog/index.php on line 17”

“Fatal error: require() [function.require]: Failed opening required ‘./wp-blog-header.php’ (include_path=’.:/usr/local/php5/lib/php’) in /home/content/74/7000374/html/Blog/index.php on line 17”

the page address is http:/www.advancedthermal.com.au/Blog.php
the blog address is http:/www.advancedthermal.com.au/Blog

Can anybody help!!!!!
Thanks in advance