To change your password, follow the steps below:
From the side menu select Settings.
Next, select the Account settings icon.
From here, select the Change password tab.
Enter in your old password in the appropriate box, then enter in the New password in the next box. You will need to repeat the new password to ensure you have entered it correctly.
Then press the blue Save button.
If you cannot remember your password, follow the instructions here to reset it.