title: How do I add a new sheet to an Excel .xlsx file using the OpenXML SDK v2.0 with c#?
body: <p>Just posting the solution I worked out today. See my answer below. </p>
  
  <p>If you don't have the very helpful OpenXML SDK v2.0 Tool, you can find it at <a href="http://www.microsoft.com/downloads/details.aspx?FamilyID=C6E744E5-36E9-45F5-8D8C-331DF206E0D0&amp;displaylang=en" rel="nofollow noreferrer">http://www.microsoft.com/downloads/details.aspx?FamilyID=C6E744E5-36E9-45F5-8D8C-331DF206E0D0&amp;displaylang=en</a></p>
  
  <p>If you know the purpose of the lines I commented with "I don't know...", please leave a comment explaining them.</p>