The text you just read has been prepared in order to help an absolute beginner to get started with programming in Fortran 77 on Windows or MacOS X platforms. My goal was not to write a manual which would thoroughly explain a wide range of Fortran constructions, but to merely lay for you the grounds for your future study of Fortran and its application in your study and research. We omitted here many interesting parts of Fortran which can make your programming more fun. If you encounter a problem which you cannot solve based on the information you just gained, check with a good Fortran book or a devoted web site.
Remember, you will not become an experienced programmer over night, not even after two or three months of working on your assignments. Do not be afraid to use Fortran for solving more involved problems also in other courses. The best way to understand any programming language is to play with it, test different language constructions and mainly to learn from your own errors.