To access Messages you can either use the position in the menu or the bubble icon in the upper right corner.
On the left you can see the list of your conversations. At any moment you can click on any conversation and type something or send an image or an attachment.
If you click the people icon in the upper right corner, you can see who is in this conversation.
If you click on the pencil icon, you will be able to start a new conversation. You can message up to 30 people and you can search by their first and last names or job positions.
Choose people you want to talk to and click Let’s talk, your conversation is ready.