In your terminal, type:
scp your_username@remotehost.edu:foobar.txt /local/dir
replacing the username, host, remote filename, and local directory as appropriate.
If you want to access EC2 (or other service that requires authenticating with a private key), use the -i option:
scp -i key_file.pem your_username@remotehost.edu:/remote/dir/foobar.txt /local/dir
From: http://www.hypexr.org/linux_scp_help.php