I didn't see the question about the 5.1. Some speakers will have all of the cables, and you will probably find that on the back of the mobo on the I/O ports, the sound ports will have at least 3 different ports - all 3.5mm but one is green, one pink and one light blue. Green is sound output, pink is mic in, blue is line-in. Any other colours are for your 5.1 sound, you will have to refer to your mobo or speaker manual for which port corresponds to which speaker. Each colour is standardised to be a side, rear, front and central bass speaker, but I can't remember which is which. It will say on the I/O backplate too.
There may only be the green port for output, and this is still ok. If your speakers came with all separate cables, rather than they all plug into the sub-woofer and then that has a single green ended 3.5mm cable, it may have come with an adapter that has all cables plugged into it, and on the end is a male 3.5mm green output cable that will plug straight into your mobo sound output