How to connect "Thunderbolt to Firewire adapter" to my WD external drive--

There must be a real simple answer to this question - I bought  new Mac but the 400/800 firewire cable which used to connect directlly to the MAC, does not fit into the adapter plug. Is there yet another adapter that I need to connect?

Norker

Hello,

What is the connection available on your computer and what’s the model number of your hard drive?