title: Exclude folder from github
body: <p>I need to exclude the folder App_Data from my Github but i don't know how.</p>
  
  <p>I have a application which saves many files like jpg files in the directory: Source\MyProject\App_data\stored\filename.jpg</p>
  
  <p>Now i need to exclude this from the .gitignore file</p>
  
  <p>I don't know how to do this so i am looking for a example</p>