How to learn social media marketing?

You don't apply to social media. It is simply the act of gaining traffic through Twitter and Facebook, because people will tweet about your content or facebook 'like' it to their friends.

Social Media is marketing online through websites such as facebook, twitter etc

I just said that.

thers's so much social media such as facebook， twwiter， linkedin and so on

Social networking sites like Twitter, Facebook, YouTube and blogs allow individual followers to “retweet” or “repost” comments made by the product being promoted. By repeating the message, all of the users connections are able to see the message, therefore reaching more people. Social networking sites act as word of mouth. [4] Because the information about the product is being put out there and is getting repeated, more traffic is brought to the product/company. [5] Through social networking sites, products/companies can have conversations and interactions with individual followers.

Social media marketing is today's most used marketing tool in many businesses. Usually they hire marketers who are well educated and really understand about social media. There were times that they also hire virtual marketers who will bring additional effort in branding and marketing. There are so many benefits in social media marketing but of course, people who will engage in it should be ready and plan it well. A good market can not be achieved in one night only. So thorough studying and learning about social media marketing is necessary.