Are you solo mining or mining in a pool? If you are solo mining, then you will receive bitcoins when you solve a block. At 30 kH/s, that might take a very long time. If you are mining in a pool, then the pool's website will give you the information you are looking for.

At 30 kH/s, you are going to earn something like $0.13 per day, and that is not likely to pay for your electricity.