In the sidebar on the left side of your screen click on the "Profile" link or icon.
You will see a few options for adding details to your profile and modifying your current settings:
My Details: Add an image avatar for your account or continue to use the default letters provided. Update your username here and when you're finished click the "Update Profile" button.
Email: To update your email address, enter it twice here and click the "Update Email Address" button.
Password: Change your password by entering your new password and confirming it. Once confirmed, click the "Update Password" button.