title: How to extract a link using xpath
body: <p>I'm trying to make an application where you input a web url (<code>http://www.explosm.net/comics/3104/</code>) and it automatically saves a string with the first link it finds given the xpath (<code>//*[@id="maincontent"]/div[2]/div[2]/div[1]/img</code>), which is a picture I want to download. </p>
  
  <p>I honestly have no clue where to even begin with this. I've tried the <code>HtmlAgilityPack</code> and the <code>WebBrowser</code> class, but I couldn't find anything to help me understand what to do and how to do it. </p>
  
  <p>Any help will be greatly appreciated.</p>