Copy a file from a local machine to a remote machine:
scp /path/to/local/file username@remote_host:/path/to/remote/directory
Copy a file from a remote machine to a local machine:
scp username@remote_host:/path/to/remote/file /path/to/local/directory
Copy a directory from a local machine to a remote machine:
scp -r /path/to/local/directory username@remote_host:/path/to/remote/directory
Copy a directory from a remote machine to a local machine:
scp -r username@remote_host:/path/to/remote/directory /path/to/local/directory