For one, that diagram kinda sucks.
The vertical, heavy black bar at the top of the DPDT relay is supposed to be the coil.
The arrows in the DPDT relay are supposed to be the moveable contacts.
The vertical series of 4 black dots are the connections that the moveable contacts switch between.
I have taken that image and marked it up.
There will be 8 pins.
2 pins for the coil (#1 and #2 in my image)
1 pin for each moveable contact (2 total) (#3 and #4 in my image)
2 pins for each moveable contact to switch between (4 total) (#5-#8, notice that #6 is not used)
The only thing that is missing is what terminals to connect the wires to on YOUR relay.
There should be a diagram moulded into the side of the relay to show which numbered terminals are connected to the coil, the moveable contacts and the rest. If not, there is no possible way to know what connects to what. In that case, the cap of the relay should come off so you can physically see what is connected to what, and go from there.
