This tutorial assumes that you've already logged in to RoundCube webmail.
Now let's learn how to mark messages as read or unread.
Both messages in the Inbox folder are currently marked as Read... you can tell this because the text is regular instead of bold.
Let's highlight one of the messages.
Click the Mark dropdown icon.
Let's choose to mark this message As unread.
The message is now marked as unread (since its text is bold), and our inbox shows 2 message as being unread.
Selecting an unread message will not change its status to Read.... but if the message was already selected, you can mark it as Read by choosing the option in the Mark dropdown icon.
This is the end of the tutorial. You now know how to mark messages as read or unread in RoundCube.