There are 4 major listing companies. Acxiom is the only one that lets you do this for FREE. Similiar companies charge as much as 75.00 a month. You will need your tax ID or social security number for when you register. Also if you have a brick and mortar location they will verify you are real by calling in on your business phone, so keep your login and password handy.
What do you get for the time invested? 250 distribution partners, over 80 internet yellow pages and submission to all major search engines. So take the time to fill in a full description using all your best keywords. You may have to come back in a week to finish as they will not make your account live right away.
So SEO is important to you then you need to take the time to go to https://mybusinesslistingmanager.myacxiom.com/
If you have already do this. Share it with a friend in business, this is one of the best-kept secrets to help a business get found online.