Weapon Skins Help

Hi,
I've been playing CS: GO online recently and seeing these crazy weapon skins on peoples guns. How do I get these? Do I have to pay for them? Do they require keys like in TF2?

Please help.

I didn't find the right solution from the Internet.

References:
www.neoseeker.com/forums/55074/t1995126-weapon-skins-help/
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Thanks