thumbnail picture

Hello! I’m fairly new on wordpress. Would need some help. In my post page i have thumbnails of 150 x 150. What do i have to do to click on them so it bring me the the full article and have the thumbnail in full size. it is the same as when you click read more and bring you to the full article again with a bigger image.

Thanks!
http://www.les-douleurs.com
Michel