I can see other members with a personalized profile picture. How can I change mine?

To change your profile picture, you need to be logged. Click on the ACCOUNT button in the website upper right corner. Then, below your photo or default image used, click on the "View profile". By clicking on the picture, you are able to upload a new picture from your device if it is the first time you're doing it or you can change or remove the previous photo.
Don't forget to apply by clicking on the UPDATE PROFILE button!