Can someone tell me how this works?

i made a twitter yesterday and i want to know how does ';tweeting'; actually work?????!!!!!!!!!!!!!!!!Can someone tell me how this works?
When you sign up with Twitter, you can use the service to post and receive messages to a network of contacts. Instead of sending a dozen e-mails or text messages, you send one message to your Twitter account, and the service distributes it to all your friends. Members use Twitter to organize impromptu gatherings, carry on a group conversation or just send a quick update to let people know what's going on.