You can update your personal information, including, but not limited to, your password and mailing address directly from the Account Details page which is found under My Account > Account Details.
To update any section click the arrow to open it up to see what is listed in that section: 
Then click the Edit button: 
On the edit page you will be able to update those fields.
You can change your password under the Security section by clicking the orange "Change Password" button.
