This paper is not intended to make you an expert on the fine points of random number theory or the deep math that accompanies it. Its more modest aim is to familiarize you with the concepts you will need to use ring oscillator-based noise sources properly. Equally important, you will learn how to instantiate a practical seed generator in low-cost FPGA technology and some simple techniques you can use to verify the actual level of entropy (security) your design will produce for a particular application.