Yes! If you want to Private message someone, click the envelope icon located at the top right of the page. In the bar that says “New private message” enter the username to whom you want to send a message. When you see the user's name, click on it and press enter. (You can make group chats as well by adding more usernames to the list) Once you're happy with the list of people or the person you want to send a message to, hit enter and you'll be able to talk privately!
Note: You can add up to 9 users to a group chat.