Error message: "Error 404 Page Not found"

Hello, I have installed WordPress site and a theme Statua with help from my hosting company. The problem is, anything I install on the first page, results an error messages like this:
1)Error 404 – Page not found!
The page you trying to reach does not exist, or has been moved. Please use the menus or the search box to find what you are looking for.
2)Warning: getimagesize(/kunden/homepages/23/d302698306/htdocs/Wordpress 3.2.1/wordpress 3.2.1/wp-content/uploads/2011/09/Gravatar-1472-150×150.jpg) [function.getimagesize]: failed to open stream: No such file or directory in /homepages/23/d302698306/htdocs/Wordpress 3.2.1/wordpress 3.2.1/wp-content/themes/statua/functions/admin-functions.php on line 565.
3) I received following notes from my hosting company, but they don’t seem to be able to help any further on this. After I deleted my Gravatar, the Warning (item 2 above) stopped, but I am not able to post anything on my site.
Would anybody have advice or instructions for me, what should I do next. I do not have computer training, but I can follow instructions more or less.

My site addresses: http://s302698317.onlinehome.us
file:///C:/Users/Arvo/Desktop/Hello%20world!%20%20%20Internet%20Market%20Deals.htm

I appreciate any help.