To obtain skins through the Steam trading system, your account must meet several requirements.
Make sure your account has:
1 Steam Guard enabled
2 Public profile and inventory
This can be translated as "This case is for those who love to tickle, umm... their nerves. It contains skins that have been hardened in battles for years, the most beat-up and scary skins, all collected in one collection. If you want a cool skin for cheap, then there is nothing better than getting the worst one. If you love it when the entire server laughs at your beaten-up skins, then this case is for you. Even the poorest player with a standard knife will be laughing at your cheap trinket, but only you know the truth that is inaccessible to many. A good show-off is worth more than money. And if you want to get the best skins for cheap, then this case was created specifically for you."