Either you own 21's embedded Bitcoin device which can mine Bitcoins itself or you buy them from one of the myriad of exchanges. http://circle.com http://circle

Either you own 21's embedded Bitcoin device which can mine Bitcoins itself or you buy them from one of the myriad of exchanges. http://circle.com http://circle.com or http://coinbase.com http://coinbase.com for instance. Also, "The easiest but most limited way to get some bitcoin with 21 is to run 21 faucet, which gives you a small amount of bitcoin to play with."