There are a number of resources that can help with your introduction to model rocketry. Probably the best book you can get is the "Handbook of Model Rocketry" by G. Harry Stine. You should be able to find it at your local library. It is also available online at many retailers. (It''s even available for the Kindle reader!) This book covers almost all of the information that you will need to get started.
There are also many online sources too. Here are a few: