I have occasion to need to FTP data in order to integrate it. Usually I use the FTP components that come with .NET, but they don't handle SFTP. It's a changing world.
The code sample below shows how to use the Renci.SshNet dll. It's free, here:
https://github.com/sshnet/SSH.NET
If I have occasion to need this again I'll blow it out into a full class, but for now I just need the upload.