You can express your likings of a post by clicking on the thumb 
. When you move your cursor over the thumb, all the people that liked the post will be visible. You can also add a reaction with a text message underneath the post. You can do this by typing your message in the text box and clicking on the send button 
. Here, you have again the option to add an approver 
, add an emoticon 
, inline a picture 
or add a file 
.