Once you are logged in and the portal loads, click on the account picture circle in the top right corner of the page. If you don't have a picture uploaded, it will usually default to your first and last initials.
Choose "view account" from the menu that pops up.
This will load a new page with your account information. Look for the tile that says "Password" and choose the "change password" option.
A new screen will load walking you through changing your own password, just follow the on-screen instructions.