Upload a file on a Sharepoint website through c#

I've a file library on a sharepoint 2010. I'm using the Sharepoint library and I want to upload a file.

I found a lot of example about this, the problem is that I've some additional fields in the sharepoint file library, and I don't see how to specify them.

Here is one of the example I saw: http://msdn.microsoft.com/en-us/library/ms454491.aspx

One of these fields is mandatory so I've to set it when I add a file.

How can I do this?

Thank you!

Here is a sample of how you might do this ("Method 2" in the example):

http://www.learningsharepoint.com/2010/07/12/programmatically-upload-document-using-client-object-model-sharepoint-2010/

In a nutshell, you need to upload the file first and then update any required metadata fields.