It's possible to upload images and files for use in your theory page.
Uploading images
Images can be uploaded from the "General" tab above the toolbar. Click the blue "Add files" button to choose the files you want to upload.
Make sure to click the "Start" button to upload the files.
After the upload, a link will appear that you can use to reference the upload:
Placing images in your theory page
In the toolbar, click the Insert button. Choose "Image" in the drop-down menu. A pop-up window will appear with some options.
Paste the reference link in the field labelled "Source" or choose the correct file from the list labelled "Image list".
If you want to only display a small image, but you want the student to enable to zoom it, you can set the "Dimensions" in pixels (or scale with the mouse after inserting the image), and apply the class "Zoom", also available in the insert/edit image from the editor menu.