how to implement like and share button step by step inasp

These features are database-oriented services where users store their records and you consider them a Like. For example you can store a record of UserID and ContentID in the Likes table then consider them as a Like by UserID on ContentID. 

TABLE Likes
UserID | ContentID 

All you have to do is to handle the event (such as button's click event or form submit event) and then create a new record for that UserID and the ContentID that you want to store. Each record would represent a "Like" by a user on a content. 

 

Same happens for the Shares, you store the UserID and the ContentID that a user is sharing. Of course you can add more columns as per your need, but that is not the topic is it? :-)