php problems for installation

I’m stupid and hopefully this is very obvious. I have tried to install wp. I use a database I created on my server at Webfusion. I have copied all the files carefully to a subdirectory of my website on the server called ‘blog’. I have renamed the config file and added all the database info. When I tried to raise the install.php on the web it couldn’t be opened: generic ms error msg saying the file could not be opened or does not exist. Then tring to open the php files (any of them) locally out of my d: drive also doesn’t work – they won’t open. Clearly this is something fundamental and not wordpress specific. Is it permissions? Don’t see why I should have to change them but if so then how? Is it the server or web browser? Help needed.