>Shy people often do really well in online classes. You can take as long as you want to reply to a discussion. You can ask questions without being concerned what other are thinking. You can even do class work in you pajamas if you wish.
I really encourage everyone, but particularly people who think of themselves as shy, to actively participate in the discussions. This is a great way to put yourself out there and challenge yourself to try something that is difficult for you in a face-to-face class.