Dokuwiki uses a simple wiki markup language. To format your text as you write it, you can either use the editor shortcuts or manually type in the syntax. Additionally, help pages exist at wiki:syntax that you can reference.

Clicking on the icon of a framed picture will allow you to upload and add files to the page. These can be images or other files such as PDFs, Word documents, archives, etc.

Clicking Save will save the text you've entered. Preview will allow you to see how the page will look but it will not save it.