Clicking on your user name in the upper right hand corner of the website will bring up a drop down menu. In that menu click on the password and security link:
If you're on a mobile device, tap the hamburger menu (the three lines in the top left corner):
This will open the main menu for navigating the website. Next, tap on the person icon as shown below:
Here you'll see a list of links where you can see various information about your account. Tap on the password and security link to continue.
If you're still having trouble, here's a direct link to the page:
Enter your current password in the top field, and the new password you would like in the fields below. You will have to enter it again in the second field to confirm the new password:
Click the Save button.