Strange that Coolermaster didn't give you one big plug with the wires all laid out. This is one header that's pretty much standardized. But whatever. If you want an authoritative answer, ask Coolermaster, but here's my hunch:
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As you can see with your own eyes, L-RET and L-OUT are electrically connected, so they're the same thing. Stick them on the BLINE_OUT_L and Line out_L pins, doesn't matter which is which if they're both riding the same wire.
Ditto for their twins with letter R instead of L.
The GROUND wire from that group, plug into the NC pin.
On the MIC group, my guess is you should leave the +5VA pin vacant and plug the MIC-POWER wire onto the MICPWR pin, the GROUND pin onto the AGND pin, and the MIC-IN wire on the MIC2 pin.
Again, if you're wanting an authoritative answer, then it would be good to get that straight from Coolermaster