How can I open a member's profile from the chat?

Right-click on a name in the user list to open a menu. The first option is 'Profile from nickname'. Click on this to display the profile.

You can also click on the user name in the list once with the left mouse button. The "To profile" button is then displayed at the top of the list.

If this does not work, please check whether your browser is blocking pop-ups.