You can change your password using the "User Menu / Change Password" link on the upper right corner of the Application Server: https://programming.cmpe.boun.edu.tr .
Please use the "Send New Code" button to receive a password reset verification code in your e-mail, if you can not remember your current password.
You can also change your password using the "Change Password" section of the Teaching.Codes plug-in.
Passwords are secured, however, you should not reuse your passwords of other platforms and web sites in your Teaching.Codes accounts.