Ok, so you have 1 sub which has 2 4ohm voice coils and a 2 channel amp.
Wire them like this to make your amp see a 2ohm load:
If you want to bridge the amp to get the power from both channel into the one sub:
Wire the positives from the sub to the positive on one channel of the amp.
Wire the negatives from the sub, to the other channel of the amp negative terminal.
This will be at 2ohm mono.
BTW, If you don't wire it bridged, you are just wasting the other half your amp.
So I would wire it bridged into mono, unless your sub cant take the wattage.
This will help you, bookmark it:
http://www.rockfordfosgate.com/rftech/woofer_wizard.asp
P.S. Bridging an amp does not effect ohm load.
The increased wattage output in a bridged setup comes from both channels being dumped into one, not a lowering of the ohm load.
BTW, Your Pic 5 would be 4ohm stereo. Each voice coil is 4ohm, running one to each channel of the amp would make it 4ohm stereo.