OK, take two and you need to wire them in series.
I assume the wires are marked... I can't tell from the picture, but let's say one is yellow and the other is black.
Take a yellow wire from speaker 1 and attach it to one radio wire (doesn't matter which). Now take the black wire from speaker 1 and attach it to the yellow wire on speaker 2. Take the black wire from speaker 2 and attach it to the unused radio wire.
You now have 8 ohms impedance.
