title: Need some help starting off with MongoDB
body: <p>I am starting off with mongodb and need some help getting some facts straight before I can continue to work on this project.  The questions are listed below, and I appreciate any and all answers :)</p>
  
  <p>Thanks!</p>
  
  <ol>
  <li>How do you create a collection in advanced? From what i understood
  the collection gets created when you insert a document for the first
  time.</li>
  <li>And what types of indexes are there?</li>
  <li>Lastly, there are no joins in mongodb like there are in mysql. Let's say i'm trying to build a
  basic private messaging system. I want to have 2 collections
  (tables). One that lists the participants in a conversation, a
  unique id for the conversation, and another collection for all of
  the messages for that conversation. In mongodb is it wiser to nest
  the second collectino into the first as a sub-column such as
  "messages"? Or am i better off keeping them separate? Is it possible to update a subcolumn with new rows? let me link a quick exmaple of what i am talking about 
  <a href="http://pastebin.com/gzKDNwnU" rel="nofollow">http://pastebin.com/gzKDNwnU</a> </li>
  </ol>