Can someone help me out with how to limit ssh access to one IP address using IPtables?

The easiest way would be to use tcp wrappers... you will need to edit your /etc/hosts.allow and hosts.deny file. If you want to block ssh you can figure it out by getting my iptables configuration script off of www.sekure.us or by reading up on tldp.org (search for "tcp wrappers" or "iptables" based on how you want to do it... tcp wrappers would be easiest though)