Twitter has a lot of following - over 700k users. I get asked about "Twitter" and want to provide some basic info.
As I was looking for resources I found a lot of people have written awesome twitter guides. You can skip the next few paragraphs and go directly to the links below for Twitter guides.
Twitter if free. You to to Twitter.com and signup. Most people have a picture a URL to their website or blog and 160 characters worth of information about themselves.
A first time user of Twitter will find it difficult to understand Twitter and may give up easily as the Public Timeline will not make sense at a glance. If you walk into a large room where there are several conversations going on simultaneously the feeling is the same.
How to you join the party? Just like you would in the real world. Find a conversation that interests you and follow it. As you look at more and more "Tweets" ( The updates you make on Twitter which are limited to 140 characters) you will find some refer to something that interests you.
If you would like to reply to someone's comment you add "@" as the first character and then their Twitter username. This will ensure that your reply goes to their "replies" tab even if they missed your Tweet.
There is a a way to send direct messages that will not be seen by anyone but you and the receiver. To send a direct message "DM" you type the letter d and after a space type the person's username and then the message.
If you have a friend who referred you to Twitter then chances are that they will introduce you on Twitter and you get some instant followers. If your tastes are similar you can look at the people they are following and choose to "follow".
The term "Follow" means that you are agreeing to see their Tweets in your start page. The more people you follow your home page will get more crowded.
Using Twitter screens you can click on the persons username and the next screen will show a "follow" button. You can also follow a person by just typing " Follow" followed by their username.
There are several reasons that people are there on Twitter. Many I think are there for the conversation. Whatever reason you are there if you practice common sense good practice you should be fine.
Rafe Needleman's Newbie's Guide to Twitter.Jason Lee Miller -Twitter + Etiquette = Twitterquette?
Read Write Web: The RWW Guide to the World's Most Popular Twitter Clients
Twitter - A one minute Primer - Peter Shankman
To be Fair here is a guide to Jaiku by Robin Good