Some time ago I blogged about How to: Uploading a File to a SharePoint Library Site from a Local Folder and How to: Magic with SharePoint 2003, uploading files using a Web service . Some people found these samples useful and some people asked if I could provide sample code that works with SharePoint Server 2007. For some time I asked around and realized that there are multiple possible ways to accomplish this task in SharePoint 2007.
See original here:
How to Upload Files to SharePoint Server 2007 from ASP.NET Web Applications