scp somefile.txt -i mykey.pem root@ec2-184-73-72-150.compute-1.amazonaws.com:/

Password:

scp -i  mykey.pem somefile.txt root@ec2-184-73-72-150.compute-1.amazonaws.com:/

scp -i /path/to/your/.pemkey -r /copy/from/path user@server:/copy/to/path