title: How to make a second github pull request when one is already pending
body: <p>I've used other revision control systems before but have little experience with git and github.</p>
  
  <p>I wanted to contribute to a project, so I forked it on github, fetched a local copy of my fork, edited it, committed it, pushed the change back to my github fork, and opened a pull request for the original upstream author to look at.  That all seems fine.  The author said he'll get around to using it in a bit.</p>
  
  <p>But now I want to address a second issue of the project with a second pull request.  But everything I commit and push ends up being appended to that first pull request.  What I want to do is make a new second pull request for the subsequent changes, while the first pull request is still pending and not merged in to the upstream yet.</p>
  
  <p>What steps do I need to run to do that?  I'm using git-bash.</p>