title: How can I get specific date in a year?
body: <p>I wanna make a lesson scheduler. For example all friday's lessons same and should show on scheduler. How can I get all friday's date in a year? 
  I have some datafield for this ;</p>
  
  <pre><code>-Dayofweek  int
  -Starthour  int
  -finishhour int
  </code></pre>