upload file to server

Hi there, I am using the File class in .net (c#) to upload a file to a web
application using File.Copy(<file i specify>,<new location>). When i use my
app locally, choose a random document from my file system, it works fine and
i end up with two of the same documents in diff locations. When I do it on
our server it says it cant find the file (obviously my input=file control
does a browse on my file directory but when it goes to do File.Copy it cant
find the file in its own directory system as its the server not my machine).
Is there something else i must do to say 'not only look for file on client,
but take file.copy from client machine aswell). not sure how. Anyone had the
same problem (not a bug i just could do with someone to tell me how they did
it)

Thanks.