To participate in a race you need to check many aspect of you bicycle and your own body. Bicycle is a human powered device and therefore your body build must be adequate for bicycle race. The first thing you need to pay attention to is your fitness. You will need to beadle a lot to achieve the speed you desire. In order to be fit, you will need to practice using a treadmill and monitor your heart as well. Asking for a professional trainer is mandatory to overlock your abilities.
Once you are fit to race, you will need to tweak your bicycle. First, you need to have either a road or a racing bicycle because they are the lightest. Reducing your bicycle weight is important to maintain a high speed and easy beadle.
Last advice is to be modest and not to think about racing as competitions but as a chance to enjoy a great hoppy and sport. You will be the winner for believing in that.