If you haven't already, start SourceTree. Then, do the following:

• Choose Clone / New from the menu bar.
  The system displays the Clone / Add Create Repository dialog.
• Enter a Source Path / URL.
  You can enter the URL for a remote repository on Bitbucket here. Try entering the URL for your bb101repo, for example:
  <a href="https://tutorials@bitbucket.org/tutorials/bb101repo">https://tutorials@bitbucket.org/tutorials/bb101rep...</a>
  The system requests a username password.

• Enter your password and press Login.
• Press Clone.
  SourceTree returns you to the main window: