Log in to your Netflix account. Do this by visiting the Netflix website and then entering your username and password.
Select a movie and click on it for more information. It really does not matter which one you select since you will just be using it to access another page. Wait for the movie information to load.
Go to the "Member Reviews" section on the lower right-hand side of the page. You will see a button that says, "Write a Review." Select this option. You will not have to write a review.
Click on your avatar. It has either been set by you or by Netflix. It will appear next to the text field where you can enter your review.
Find the word "Edit" on the page that loads and click on it. It will be located directly under your avatar.
Using the dialog box that appears, select a photo that you would like to use and press "Open." This will upload your new avatar.