You can also message people on Facebook. For this you just need to click on the envelope icon in the blue ribbon on extreme right corner. This will allow you to land in a window like one shown next.
Apart from the text, you can use following message options
These include sending pictures, small videos called GIF’s, emojis, voice notes, or web cam picture too respectively. At the end you can see a thumbs up, that can be use to send a thumbs up in message.