Do not become overly dependent on your calculator. It's a very useful tool for complicated calculations, but you should be able to do the basic computations and manipulations in calculus without a calculator or at most, just using it to help out with tedious arithmetic. Calculators may or may not be allowed on quizzes/tests in particular courses: check with your instructor about the course policy. Generally, calculators with a built in CAS (Computer Algebra System) are not allowed on tests and quizzes.
The following files may be useful in beginning calculus courses. The instructions are written for the TI-83 calculator, but the methods may be similar on other Texas Instruments models.