Your vision carriers are already added to your account when you sign up! If you want to opt-out of certain carriers, this is how you do it:
1. Click on your profile image in the top right-hand corner of the webpage
2. Select "Carriers"
3. Click the "X" in the top right-hand corner of the carrier you would like to opt-out of.
4. Press "OK" in the pop-up dialog box