Welcome to the board!
If you look to the right (below my post) you will see the arrow and Reply
If you want to quote what someone else wrote you hit Reply with quote arrow.
I don't know what that third one does! I never used it
I just clicked on the " and it says multiquote. I think that means if you see 2 or more things people write and want to include them in your message.
Hope this isn't clear as mud!