Upload files with HTTPWebrequest (multipart/form-data)

Is there any class, library or some piece of code which will help me to upload files with HTTPWebrequest?

Edit 2:

I do not want to upload to a WebDAV folder or something like that. I want to simulate a browser, so just like you upload your avatar to a forum or upload a file via form in a web application. Upload to a form which uses a multipart/form-data.

Edit:

WebClient is not cover my requirements, so I’m looking for a solution with HTTPWebrequest.