Import a file (image or pdf) in your document.

To import a file in your document, right click on your document background and select "Import file".

Within the file browser, select the file to import and click on "Open".

You can also do a drag and drop of your file directly in your document from a file browser or from your desktop. For that hold the left click and slide your file above your document. This technique also works to send files directly in a portal (slide your file over the portal).