title: How to select text from the RichTextBox and then color it?
body: <p>I want to create a simple editor like <a href="http://en.wikipedia.org/wiki/Notepad_%28software%29" rel="noreferrer">Notepad++</a> with simple functionality... I need to color a specific word in the rich text box area. How can I do that? </p>
  
  <p>For example: when the user write these word, I want to color them to the blue color. These words are: <code>for</code>, <code>while</code>, <code>if</code>, <code>try</code>, etc.</p>
  
  <p>How can I make the richtextbox to select a specific word and then color them?
  And, if I want to make a comment and color everything after the <code>//</code>, how is that done in the richtextbox?</p>
  
  <p>How do I number the line in the text box, so I can now the line number when I'm coding in my editor?</p>