What do I do with this? I got excited at first because I thought I got a free copy somehow, but i realized the truth. But now that I have it, I do not know what to do with it.

To get the "badge" Steam wants you to collect the other 9 cards through various means. The easiest way is to buy them on the marketplace. You can get them for free via voting or trading other cards you own or games and such, but the main method would be to buy them. If you care about that sort of thing, that is.

Welcome to the new Steam microtransactions.

If you manage to complete the "set" you can craft them which gets a badge for your profile and a profile background I believe. Also chat emotes.

@super2j: Go read the FAQ on steam about Trading Cards or read the Wiki here about it.

You trade it to me for one of my three Torchlight II cards.

Bravo to steam for trying new things, but this trading card stuff is dumb, I really can't ever see myself bothering other people to trade for completely pointless rewards.

It's actually cheaper to buy them on the marketplace than to collect them by spending money in the sale. If it's one free card per $10 spent or buying a card for thirty cents, I know which I'd choose (did choose, have chosen.)

The very cheapest way to complete the sale set quickly is to buy McPixel or Hotline Miami cards at ten cents each and then craft their badges for an emote, a wallpaper and a sale card for every badge crafted.

Spending $10 during the sale might be a decent deal, as long as you're interested in whatever you're buying. But if you're only interested in the cards, don't bother with that method.

So sell them then and get money out of them.