Most known Social Media to promote your business are:

Facebook
Set up a business page on Facebook and post special offers, at least once a month, to all those who Like your page.
Create a Facebook Page where people can become a fan of your business, post comments on your products or services, chat  or talk with you and share content with their friends.

Twitter
Use Twitter to tweet interesting facts about your business or products and provide a link to that product page on your site. By searching for topics that interest you and are relevant to your business you can quickly build up a network of people to follow and build up your own tribe of followers.

YouTube
Your business can use YouTube to post individual videos about your products or services, or also you can  create you own YouTube Channel, which contains a collection of videos related to your business area. Add regularly and useful videos and then encourage customers to view and share your videos with others.

Google+
Create circles in your personal Google+ profile that are set up specifically for your customers, your vendors, and others interested in your brand. Launch a Google+ profile,  to make it easy for your customers to find and follow your business.

LinkedIn
Create a LinkedIn profile and add links to your website; update your profile with new links, product reviews, books, or articles that you're reading, or other information so that this information appears to all the people in your network.

Therefore, by using these social media networks you can reach more visitors to your web site by sharing links, articles, so on. You can increase the number of sales by sharing of the products or services you offer. Also, you can create your brand name in the online environment.