Yammer makes it easy to engage with others, and keep the conversation going wherever you are.
Like a post
Acknowledge someone’s point, agree with an idea, or show that what they’re saying is helpful.
Reply to a post
Add you insights or ask a question.
Select REPLY and write a response.
@mention people who can contribute to the conversation or would find it useful.
Notify additional people if you like.
Select Post.
Share a post
Select SHARE.
Select Post in Group or Send Private Message.
Select a group.
Type a message, and then select Share.
Source: Microsoft