title: Running 'commands' to install open source software
body: <p>Not sure how to phrase the title of this question as not having a clue what i'm trying to describe is part of my problem. Here's what I mean: I often come across tutorials or open source software that will say something like this:</p>
  
  <pre><code>// Install PHPDocumentor
  $ pear channel-discover pear.phpdoc.org
  $ pear install phpdoc/phpDocumentor-alpha
  
  // Install phpunit
  pear install pear.phpunit.de/PHPUnit
  
  // Install Magento Ecommerce
  svn checkout http://svn.magentocommerce.com/source/branches/1.7
  </code></pre>
  
  <p>This may seem like a basic question, but where exactly do I enter these commands? </p>
  
  <p>I'm using windows 7. If I attempt to enter these into the Windows Command Prompt I just get an error like 'xxx is not recognised as an internal or external command.'</p>
  
  <p>It's frustrating because a lot of websites use these commands as instructions to install or upgrade their software.</p>
  
  <p>I'm assuming the reason none of these websites explain where to run the code is because it's common knowledge, so sorry again if this is a basic question.</p>