Today you will become Wikimedians.
We’re glad you wish to help develop Wikipedia, and we hope you enjoy participating in this virtual community as much as we do. As a new contributor, you may feel a little overwhelmed by the sheer size and scope of this project (which includes over 100,000 regular participants), but don’t worry, things will become easier and clearer as you go, and if you have any problems, there will always be other Wikipedians happy to help. There are some resources set forth below to help you get started. Good luck and have fun!
If you do get stuck, there are volunteers available to answer your questions. There is also a tutorial that can guide you step-by-step and a comprehensive list-style overview of help related pages at Help:Contents/Directory.