CME doesn't sell bitcoins (or any crypto currency for that matter), this is talking about a USD denominated derivative that pays out based on the price of bitcoin at any given day. It works very similarly to a bet, and essentially you say I think that bitcoin will cost $x on this date and whoever is on the other side of the contract either wins or loses based on where the price actually ends up. Futures are a pretty sophisticated asset class and it is really easy to get burned in them. Very few retail investors use them for speculation. I don't mean this in a demeaning way but if you are not already familiar with futures markets you should probably not bother trying to trade these.