There are basically two ways to be active in social networks: promotional or informative.
Social media marketing as inbound activity means not distributing promotional content, but providing knowledge to the social media user for free. For example, it can be a tutorial that explains what you need to know about your area. Blog articles are also easy to distribute via Facebook. The advantage: You only have to invest in the creation of content, but not in its distribution.
Social media advertising means placing paid ads and advertising on social networks. This method has the advantage that targeting makes the measure more relevant, since the ad only reaches those users who fit into the previously defined schema. The cost of social ads varies depending on the platform and preference.
The best results are achieved by combining both options.