Welcome to Wikipedia. Its wonderful that you've registered as a user and joined the wikipedian's community. Its a growing commune, with a big number of wiki-fanatics, and many more wiki-fans.
As you'll realize, behind the information and wikipedia pages that so many millions of people access and find useful, there is a huge amount of work that goes on. As you'll see, there are at least 5-10 pages that are involved in the maintenance of a single wikipedia page- Talk pages, categories, Templates, WikiProject discussions, images, and documentation pages, among others. Its a huge and sometimes chaotic system, but it works. Its an invisible cog thats run by millions of little mice like me, you and other editors, admins and experts that keeps wikipedia updated and running.
As a new wikipedia user, I'm sure that you're feeling like a fish out of water. Dont worry. Thats natural. I felt that too when I first started editing. But as you keep editing, wikipedia formatting styles and rules will become second nature to you. It may take some time (I took about 4 months and 500 edits to get used to it), but it will happen. Then, there are the ubiquitous abbreviations that seem to fly around the wikipedia- CSD, CFD, WP, 3RR, AGF, etc etc etc. Again, dont worry, they're not that crucial. you'll be able to figure them out quickly enough. And if you're not, most of them link to the page that explains their meaning.
I know how you freshies must be feeling right now, and I've tried to put down some of my experiences and tips in this page, so that you'll not find it so tough.
Why are you here?
editFirst, try and figure out what interests you in Wikipedia. Most editors join up and get involved in a specific area that interests them. In my case, its Indian scientific and Defence technology. What is it for you? This is important because wikipedians spend most of their editing time improving topics close to their heart. Identifying that topic will help make your experience easier and more enjoyable.
Wikiprojects
editGood. Now that you know what interests you, you can search for other editors who share your interests. These creatures can usually be found as members of various WikiProjects. There are wikiprojects for pretty much every single interest or subject you can find. Find the wikiproject that interests you and join it as a member. Its easy- just go to the WikiProject home page, and add your username to their memberlist; and Voila! you're a member of that group. If more than one topic interests you, you can join more than one WikiProject. In fact, you can join as many groups as you like.
Adopt-a-user
editIf you are new and need help, dont worry. There are thousands of experienced wikipedians who are willing to hold your hand and show you the way, or clear your doubts when you have any. These kind Samaritans are willing to adopt you and help you along till you find your feet.
Who are you- User pages
editStart editing
editMost registered users have been editing for some time as anonymous editors before registering. That makes things somewhat easier, since you already know a bit of Wikipedia Formatting. If you dont, dont worry. Its easy.
The best way to learn is to start making small improvements to articles. The best way is to brwose through wikipedia. If you find a grammatical error, a bad link, wrong information, or vandalism, you can edit it. By making minor edits in the beginning, you'll quickly learn the format that should be followed and the syntax of wikipedia. To edit, just click the edit button at the top of the page, or next to the section, and wait for the page to load. Once there, you can edit anything you'd like to improve.
While editing, the most powerful tool I've found is the "show Preview" button. Its your best friend.