Trying to connect ps3 via Thunderbolt

Hi all,

I am trying to connect my ps3 to my 27" iMac using a mini displayport to HDMI adaptor and I'm not having much luck. Nothing happens when I press command f2. I've never once used the Thunderbolt port so I'm not sure if I need to enable it or download software? But that doesn't seem like something I'd need to do. Anyone have any suggestions? Thanks!