1

Make a copy of your existing sshd_config file. Change directory to /etc/ssh and copy the sshd_config file to another filename. You may need to do this operation as the superuser (root).
2

Open the /etc/ssh/sshd_config file in a text editor and change the line Port 22 to Port <your new port number>. Ensure there is no '#' character in the "Port" line. This character will cause the line to be ignored and your change will not take effect. Save the file after editing.