This blog post illustrates the basics of Level 2. The first link is a quick read which will give you the basics in very simple terms.  The second link is from Tim G, one of Skyes top students.  He provides a very detailed explanation of Level 2 trading.  He pauses the video a few times to deep dive into what his thoughts are and explains things in an easy to understand approach.  There are several example videos which I found to be the best - for additional Q&A's, read the comments below each video.

This is a great resource for newbies. 

1)  A good Level 2 read

2)  Trade the Ticker

As always, if you like the post... throw me a little Karma. 

NOTE:  I am not advocating any software or services.  This is for educational and informational purposes only.