You can't.
It's possible to get some information (which may or may not be related to the company owning the website) about the company that owns the domain that hosts the IP:
http://dotnet-snippets.com/snippet/whois-lookup/668[
^]
But...many web hosting companies will host loads of different company domains, and unless they have paid extra for a static IP address they can't be tied to a specific IP: the "owner" of the IP address is the hosting company, and not the company hosting the website on that IP. Even if it is a static IP, the physical location details will refer to the hosting company location: which can easily be on a different continent to the company "owning" the website (mine is, for example, in Nevada, and I'm in Wales)