First of all wiki uses markup language to create pages. That said I have used it with html blocks since i know very little about markdown. The screenshot is under the Pages mod selecting the wiki menu on the left. There were three block on default page when I opened it, but you can create a new page or learn how to create new blocks from scratch which is which is a whole another discussion. I mess around with it using markdown to make a table of contents on the left and help  text on the right for little time and quit and used html blocks instead.