Setting up a new mac mini

I have just arrived in Greece with a brand new Mac mini, with wireless keyboard and magic trackpad... bought in Manchester, UK on Monday.
I also was sold a Belkin HDMI cable to connect the mini to the TV.
So I haven't got very far .. I have connected the cable to the TV and Mac and turned on the power ... After the apple symbol comes a white box with an oval shape diagram. there is a balloon with a Green button and arrow which does not relate wither to anything on the mac or the TV????
There is nothing in the manual to explain...
Can anybody out there offer any help...