How do you sharing of a file?

Are you talking about an audio/video file or some other type of file? If you mean a written file, then I guess the best thing to do would be to email it to your intended recipient. If you mean an audio file, like an MP3, then you could try an audio file sharing website.
One of the best free audio file sharing sites is YourListen (http://yourlisten.com). This site allows users to upload and download audio files. If you're looking to upload a file into this database site, you just really need to sign up and go to their upload a file section. That page will take you through exactly how to upload a file to their site in the form of an upload wizard.
One of the best free any file sharing sites is ItsUploaded (http://itsuploaded.com), this is not strictly limited to audio though and you can upload almost anything. Just Drag and Drop your file and press upload and easily share :).

hope this helps some.