How is Bitcoin Mining done ?

I'll try to elaborate. The program itself is free and there are many of them to choose from. CGMiner is probably the most lightweight of them all, if you want a starting point. GPU (aka graphics card processing units) are the most effective to mine bitcoins looking at it from standard PC hardware. In this fashion, electric supply vs. profit is turnout is low. There are however specific hardware options specifically made to mine which use minimal power and gain significantly better performance.