To change the SSH port number login as root and edit /etc/ssh/sshd_config
You may use nano or vim to edit this.
Find the line that says Port 22 and change 22 to any number between 1024->65535 and save the file.
Once done restart the SSH server:
/etc/init.d/sshd restart
Now start a new SSH session (do not close your existing one) just to make sure that you can get in. If you can now login on that port you are succeded.