Doesn't Mac OS X have SSH as a default command line utility?
Type in
man ssh on the Terminal app on your Mac. This will give you help on how to use the SSH command line utility.
Are both computers set to connect through TCP port 22? Is TCP port 22 forwarded (unless it's a LAN SSH session)?
If you don't know what all this means, then you should either read a guide on SSH or just not use it at all. Someone with your account password and IP address can get into your account and even maliciously use
sudo (if your account is set to admin) if you don't know what you're doing with SSH.