How to access Iptables using my Macbook??

I have a DSL modem connected to a Meraki wireless repeater that sends a signal about 400ft away to the other Meraki repeater. These devices do not have port forwarding which I need to do. There is a way to do it, but I need to use iptables. My question...how on earth do I access the iptables using my Macbook?? Someone said something about telnet or ssh, but I have no idea how to do this? Do I hook up directly to the repeater just get on its wireless signal?? What commands do I use in terminal?? Help! Thanks!