Huh? You mean you're downloading blocks with the Bitcoin.exe program? Well that's just the blockchain you're downloading. When that's done, you can start mining with a GPU or a CPU (As the program itself does). After you have completed a whole block with mining, you get rewarded 50BTC. That can take a very, very very long time to complete, so most people join Bitcoin pools.
Bitcoin pools are sites setup for a large number of miners. All the miners work on the same block ,and gets their share of 50BTC for each block (According to how much they have contributed to the block)