You can easily do this after signing into your account and clicking in the top right corner on your profile picture or the default image.
Once you've clicked on your profile, you will be able to see all of your collections. On this page, click on the "edit profile" button.
Then you can click on the "Account Settings" on the right hand side.
Once in there, you can click on the default image to add your photo. Then click update to save everything.
