I cannot install wordpress on my server

Hi, i’m trying a lot to install wordpress to make a blog, but when i upload all my files including the modified config.php and then try to open the install.php on my browser, it says “404 – Not Found. The requested document was not found on this server”. I look into the install php, and it says that it cannot find the config.php file (but it is in my httpdocs directory!). Really don’t know…