For those of you who don't know how bitcoins work, your "wallet" that has all of your bitcoins in it consists of lots of numbers; these numbers are a good 150 digits long each and represent a block of bitcoins. In order to get bitcoins, you need these numbers. The only way to get these numbers is either through buying them off of someone else who has them, or to manually check every possible number until you find one that works. That is called bitcoin mining.