Many companies are now using social media to promote their business online. Social media has boomed in the recent years and is fast becoming a large part of a companies marketing strategy. Some of the main sites that are being used are Twitter, Facebook, LinkedIn and Pinterest and most of these sites do not charge or charge very little to allow you to create a profile.
Once you have a profile created you then need to get noticed and gain likes / followers etc. There are many ways that you can do this, firstly I would suggest that you get the links to your profiles displayed on your website and or other literature / sign written vehicles. Many of the public are turning to social media sites to search for a company they what to contact prior to visiting their own website!
You need offer an incentive to get people to want to follow you. Many companies run competitions either for prizes or just for fun and make sure that you interact with your audience on a frequent basis.