title: Permission denied to git push as a contributor
body: <p>Recently I have been added as a contributor to a program allowing me to make some changes but I can't git push my fixed code to the repo.</p>
  <hr />
  <p>The error is as follows:</p>
  <p>remote: Permission denied to myusername.</p>
  <p>fatal: unable to access 'program URL': The requested URL returned error: 403</p>
  <hr />
  <p>I can create a pull request to modify the file but my instructor said it would be troublesome if he had to check the request and merge them every time so he added me as a contributor.</p>
  <p>I googled my question and some said I need to add my SSH key to my instructor's account, but does it mean I have permissions to all repo of my instructor?</p>
  <p>I'm just a beginner in github, many thanks for your help!</p>